UNIVERSITY  OF  CALIFORNIA 

DEPARTMENT  OF  CIVIL  ENGINEER  C 

F*ERKCLEY.  CALIFORNIA 


GIVII 


UNIVERSITY  OF  CALIFORNIA 

DEPARTMENT  OF  CIVIL  ENGINEERING 

BERKELEY.  CALIFORNIA 


THE  NEW  HEAVENS 


Fig.  i.    The  Constellation  of  Orion  (Hubble). 

Photographed  with  a  small  camera  lens  of  I  inch  aperture  and  5  inches  focal 
length.  The  three  bright  stars  in  the  centre  of  the  picture  form  the  belt  of 
Orion.  Just  below,  in  the  sword  handle,  is  an  irregular  white  patch  about 
one-eighth  of  an  inch  in  diameter.  This  is  a  small-scale  image  of  the  great 
nebula  in  Orion,  shown  on  a  larger  scale  in  Fig.  2. 


THE  NEW  HEAVENS 


BY 

GEORGE    ELLERY   HALE 

DIRECTOR  OF  THE  MOUNT  WILSON  OBSERVATORY  OF  THE  CARNEGIE 
INSTITUTION  OF  WASHINGTON 


WITH 

NUMEROUS    ILLUSTRATIONS 


CHARLES  SCRIBNER'S   SONS 

NEW  YORK  AND  LONDON 
1922 


Ms 

ngtoewr 
Library 


COPYRIGHT,  1920,  1921,  1922,  BY 
CHARLES  SCRIBNER'S    SONS 


Printed  in  the  United  States  of  America 


Published  April,  1922 

Civ/'   D 


TO 

MY  WIFE 


493403 


PREFACE 

FOURTEEN  years  ago,  in  a  book  entitled  "The 
Study  of  Stellar  Evolution"  (University  of  Chi- 
cago Press,  1908),  I  attempted  to  give  in  untech- 
nical  language  an  account  of  some  modern  methods 
of  astrophysical  research.  This  book  is  now  out 
of  print,  and  the  rapid  progress  of  science  has  left 
it  completely  out  of  date.  As  I  have  found  no  op- 
portunity to  prepare  a  new  edition,  or  to  write  an- 
other book  of  similar  purpose,  I  have  adopted  the 
simpler  expedient  of  contributing  occasional  articles 
on  recent  developments  to  Scribner's  Magazine, 
three  of  which  are  included  in  the  present  volume. 

I  am  chiefly  indebted,  for  the  illustrations,  to  the 
Mount  Wilson  Observatory  and  the  present  and 
former  members  of  its  staff  whose  names  appear  in 
the  captions.  Special  thanks  are  due  to  Mr.  Fer- 
dinand Ellerman,  who  .made  all  of  the  photographs 
of  the  observatory  buildings  and  instruments,  and 
prepared  all  material  for  reproduction.  The  cut 
of  the  original  Cavendish  apparatus  is  copied  from 
the  Philosophical  Transactions  for  1798  with  the 
kind  permission  of  the  Royal  Society,  and  I  am 
also  indebted  to  the  Royal  Society  and  to  Profes- 
sor Fowler  and  Father  Cortie  for  the  privilege  of 
reproducing  from  the  Proceedings  two  illustrations 
of  their  spectroscopic  results. 

January,  1922. 


CONTENTS 


CHAPTER 

I.     THE  NEW  HEAVENS 


II.    GIANT  STARS       ..........         35 

III.     COSMIC  CRUCIBLES  ......     .    .     .        61 


[xi 


ILLUSTRATIONS 

FIG.  PAGE 

1.  The  Constellation  of  Orion  (Hubble) Frontispiece 

2.  The  Great  Nebula  in  Orion  (Pease) 3 


3.  Model  by  Ellerman  of  summit  of  Mount  Wilson,  show- 

ing the  observatory  buildings  among  the  trees  and 
bushes   5 

4.  The  loo-inch  Hooker  telescope 7 

5.  Erecting  the  polar  axis  of  the  loo-inch  telescope  .    .    .         9 

6.  Lowest  section  of  tube  of  loo-inch  telescope,  ready  to 

leave  Pasadena  for  Mount  Wilson 1 1 

7.  Section  of  a  steel  girder  for  dome  covering  the  100- 

inch  telescope,  on  its  way  up  Mount  Wilson     ...        13 

8.  Erecting  the  steel  building  and  revolving  dome  that 

cover  the  Hooker  telescope 15 

9.  Building  and  revolving  dome,    100  feet  in  diameter, 

covering  the  loo-inch  Hooker  telescope 17 

10.  One-hundred-inch  mirror,  just  silvered,  rising  out  of 

the  silvering-room  in  pier  before  attachment  to  lower 

end  of  telescope  tube.     (Seen  above) 19 

11.  The  driving-clock  and  worm-gear  that  cause  the  100- 

inch  Hooker  telescope  to  follow  the  stars 21 

12.  Large  irregular  nebula  and  star  cluster  in  Sagittarius 

(Duncan) 22 

13.  Faint  spiral  nebula  in  the  constellation  of  the  Hunt- 

ing Dogs  (Pease)      23 

14.  Spiral  nebula  in  Andromeda,  seen  edge  on  (Ritchey)   .        25 


ILLUSTRATIONS 

FIG.  PAGE 

15.  Photograph  of  the  moon  made  on  September  15,  1919, 

with  the  loo-inch  Hooker  telescope  (Pease)    ....        28 

16.  Photograph  of  the  moon  made  on  September  15,  1919, 

with  the  loo-inch  Hooker  telescope  (Pease)    ....        29 

17.  Hubble's  Variable  Nebula.     One  of  the  few  nebulae 

known  to  vary  in  brightness  and  form 31 

1 8.  Ring  Nebula  in  Lyra,  photographed  with  the  6o-inch 

(Ritchey)  and  loo-inch  (Duncan)  telescopes      ...         32 

19.  Gaseous  prominence  at  the  sun's  limb,  140,000  miles 

high  (Ellerman) 36 

20.  The  sun,  865,0x30  miles  in  diameter,  from  a  direct 

photograph  showing  many  sun-spots  (Whitney)    .    .         37 

21.  Great  sun-spot  group,  August  8,  1917  (Whitney)      .    .         39 

22.  Photograph  of  the  hydrogen  atmosphere  of  the  sun 

(Ellerman) 41 

23.  Diagram  showing  outline  of  the  loo-inch  Hooker  tele- 

scope, and  path  of  the  two  pencils  of  light  from  a  star 
when  under  observation  with  the  2O-foot  Michelson 
interferometer  45 

24.  Twenty-foot  Michelson  interferometer  for  measuring 

star  diameters,  attached  to  upper  end  of  the  skeleton 
tube  of  the  loo-inch  Hooker  telescope 47 

25.  The  giant  Betelgeuse  (within  the  circle),  familiar  as  the 

conspicuous  red  star  in  the  right  shoulder  of  Orion 
(Hubble) 49 

26.  Arcturus  (within  the  white  circle),  known  to  the  Arabs 

as  the  "Lance  Bearer,"  and  to  the  Chinese  as  the 
"Great  Horn"  or  the  "Palace  of  the  Emperors" 
(Hubble) 51 

27.  The  giant  star  Antares  (within  the  white  circle),  no- 

table for  its  red  color  in  the  constellation  Scorpio, 
and  named  by  the  Greeks  "A  Rival  of  Mars"  (Hub- 
ble)    54 

[xiv] 


ILLUSTRATIONS 

FIG.  PAGE 

28.  Diameters  of  the  Sun,  Arcturus,  Betelgeuse,  and  An- 

tares  compared  with  the  orbit  of  Mars 57 

29.  Aldebaran,  the  "leader"   (of  the  Pleiades),  was  also 

known  to  the  Arabs  as  "The  Eye  of  the  Bull,"  "The 
Heart  of  the  Bull,"  and  "The  Great  Camel"  (Hub- 
ble)    59 

30.  Solar   prominences,   photographed   with   the   spectro- 

heliograph  without  an  eclipse  (Ellerman) 63 

31.  The   I5o-foot  tower  telescope  of  the  Mount  Wilson 

Observatory      65 

32.  Pasadena  Laboratory  of  the  Mount  Wilson  Observa- 

tory           67 

33.  Sun-spot  vortex  in  the  upper  hydrogen  atmosphere 

(Benioff) 69 

34.  Splitting  of  spectrum  lines  by  a  magnetic  field  (Bab- 

cock)      71 

35.  Electric  furnace  in  the  Pasadena  Laboratory  of  the 

Mount  Wilson  Observatory 73 

36.  Titanium  oxide  in  red  stars 75 

37.  Titanium  oxide  in  sun-spots      75 

38.  The  Cavendish  experiment 77 

39.  The  Trifid  Nebula  in  Sagittarius  (Ritchey) 81 

40.  Spiral  nebula  in  Ursa  Major  (Ritchey) 83 

41.  Mount  San  Antonio  as  seen  from  Mount  Wilson      .    .  85 


CHAPTER  I 
THE  NEW  HEAVENS 

Go  out  under  the  open  sky,  on  a  clear  and  moon- 
less night,  and  try  to  count  the  stars.  If  your  sta- 
tion lies  well  beyond  the  glare  of  cities,  which  is 
often  strong  enough  to  conceal  all  but  the  brighter 
objects,  you  will  find  the  task  a  difficult  one.  Rang- 
ing through  the  six  magnitudes  of  the  Greek  astrono- 
mers, from  the  brilliant  Sirius  to  the  faintest  per- 
ceptible points  of  light,  the  stars  are  scattered  in 
great  profusion  over  the  celestial  vault.  Their  num- 
ber seems  limitless,  yet  actual  count  will  show  that 
the  eye  has  been  deceived.  In  a  survey  of  the 
entire  heavens,  from  pole  to  pole,  it  would  not  be 
possible  to  detect  more  than  from  six  to  seven  thou- 
sand stars  with  the  naked  eye.  From  a  single  view- 
point, even  with  the  keenest  vision,  only  two  or 
three  thousand  can  be  seen.  So  many  of  these  are 
at  the  limit  of  visibility  that  Ptolemy's  "Almagest," 
a  catalogue  of  all  the  stars  whose  places  were  mea- 
sured with  the  simple  instruments  of  the  Greek 
astronomers,  contains  only  1,022  stars. 

Back  of  Ptolemy,  through  the  speculations  of  the 
Greek  philosophers,  the  mysteries  of  the  Egyptian 
sun-god,  and  the  observations  of  the  ancient  Chal- 
deans, the  rich  and  varied  traditions  of  astronomy 


HEAVENS 

stretch  far  away  into  a  shadowy  past.  All  peoples, 
in  the  first  stirrings  of  their  intellectual  youth,  drawn 
by  the  nightly  splendor  of  the  skies  and  the  cease- 
less motions  of  the  planets,  have  set  up  some  system 
of  the  heavens,  in  which  the  sense  of  wonder  and 
the  desire  for  knowledge  were  no  less  concerned  than 
the  practical  necessities  of  life.  The  measurement 
of  time  and  the  needs  of  navigation  have  always 
stimulated  astronomical  research,  but  the  intellec- 
tual demand  has  been  keen  from  the  first.  Hippar- 
chus  and  the  Greek  astronomers  of  the  Alexandrian 
school,  shaking  off  the  vagaries  of  magic  and  divina- 
tion, placed  astronomy  on  a  scientific  basis,  though 
the  reaction  of  the  Middle  Ages  caused  even  such  a 
great  astronomer  as  Tycho  Brahe  himself  to  revert 
for  a  time  to  the  practice  of  astrology. 

EARLY    INSTRUMENTS 

The  transparent  sky  of  Egypt,  rarely  obscured 
by  clouds,  greatly  favored  Ptolemy's  observations. 
Here  was  prepared  his  great  star  catalogue,  based 
upon  the  earlier  observations  of  Hipparchus,  and 
destined  to  remain  alone  in  its  field  for  more  than 
twelve  centuries,  until  Ulugh  Bey,  Prince  of  Samar- 
cand,  repeated  the  work  of  his  Greek  predecessor. 
Throughout  this  period  the  stars  were  looked  upon 
mainly  as  points  of  reference  for  the  observation  of 
planetary  motions,  and  the  instruments  of  observa- 
tion underwent  little  change.  The  astrolabe,  which 
consists  of  a  circle  divided  into  degrees,  with  a  rotat- 
ing diametral  arm  for  sighting  purposes,  embodies 
[2  ] 


THE    NEW    HEAVENS 

their  essential  principle.  In  its  simple  form,  the 
astrolabe  was  suspended  in  a  vertical  plane,  and  the 
stars  were  observed  by  bringing  the  sights  on  the 


Fig.  2.     The  Great  Nebula  in  Orion  (Pease). 

Photographed  with  the  loo-inch  telescope.  This  short-exposure  photograph 
shows  only  the  bright  central  rjart  of  the  nebula.  A  longer  exposure  reveals 
a  vast  outlying  region. 

movable  diameter  to  bear  upon  them.  Their  alti- 
tude was  then  read  off  on  the  circle.  Ultimately, 
the  circle  of  the  astrolabe,  mounted  with  one  of  its 
diameters  parallel  to  the  earth's  axis,  became  the 
armillary  sphere,  the  precursor  of  our  modern  equa- 
torial telescope.  Great  stone  quadrants  fixed  in  the 
meridian  were  also  employed  from  very  early  times. 

[3 1 


THE    NEW    HEAVENS 

Out  of  such  furnishings,  little  modified  by  the  lapse 
of  centuries,  was  provided  the  elaborate  instru- 
mental equipment  of  Uranibourg,  the  great  observa- 
tory built  by  Tycho  Brahe  on  the  Danish  island  of 
Huen  in  1576.  In  this  "City  of  the  Heavens,"  still 
dependent  solely  upon  the  unaided  eye  as  a  collector 
of  starlight,  Tycho  made  those  invaluable  observa- 
tions that  enabled  Kepler  to  deduce  the  true  laws 
of  planetary  motion.  But  after  all  these  centuries 
the  sidereal  world  embraced  no  objects,  barring  an 
occasional  comet  or  temporary  star,  that  lay  beyond 
the  vision  of  the  earliest  astronomers.  The  concep- 
tions of  the  stellar  universe,  except  those  that  ig- 
nored the  solid  ground  of  observation,  were  limited 
by  the  small  aperture  of  the  human  eye.  But  the 
dawn  of  another  age  was  at  hand. 

The  dominance  of  the  sun  as  the  central  body  of 
the  solar  system,  recognized  by  Aristarchus  of  Samos 
nearly  three  centuries  before  the  Christian  era,  but 
subsequently  denied  under  the  authority  of  Ptolemy 
and  the  teachings  of  the  Church,  was  reaffirmed  by 
the  Polish  monk  Copernicus  in  1543.  Kepler's  laws 
of  the  motions  of  the  planets,  showing  them  to  re- 
volve in  ellipses  instead  of  circles,  removed  the  last 
defect  of  the  Copernican  system,  and  left  no  room 
for  its  rejection.  But  both  the  world  and  the  Church 
clung  to  tradition,  and  some  visible  demonstration 
was  urgently  needed.  This  was  supplied  by  Galileo 
through  his  invention  of  the  telescope. 

The  crystalline  lens  of  the  human  eye,  limited  by 
the  iris  to  a  maximum  opening  about  one-quarter  of 

[4] 


*2"AfeS 


rjc     |S"u8~^ 

II  :I?js|^l 


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THE    NEW    HEAVENS 

an  inch  in  diameter,  was  the  only  collector  of  star- 
light available  to  the  Greek  and  Arabian  astrono- 
mers. Galileo's  telescope,  which  in  1610  suddenly 
pushed  out  the  boundaries  of  the  known  stellar  uni- 
verse and  brought  many  thousands  of  stars  into 
range,  had  a  lens  about  2^  inches  in  diameter.  The 
area  of  this  lens,  proportional  to  the  square  of  its 
diameter,  was  about  eighty-one  times  that  of  the 
pupil  of  the  eye.  This  great  increase  in  the  amount 
of  light  collected  should  bring  to  view  stars  down  to 
magnitude  10.5,  of  which  nearly  half  a  million  are 
known  to  exist. 

It  is  not  too  much  to  say  that  Galileo's  telescope 
revolutionized  human  thought.  Turned  to  the 
moon,  it  revealed  mountains,  plains,  and  valleys, 
while  the  sun,  previously  supposed  immaculate  in 
its  perfection,  was  seen  to  be  blemished  with  dark 
spots  changing  from  day  to  day.  Jupiter,  shown  to 
be  accompanied  by  four  encircling  satellites,  afforded 
a  picture  in  miniature  of  the  solar  system,  and 
strongly  supported  the  Copernican  view  of  its  or- 
ganization, which  was  conclusively  demonstrated  by 
Galileo's  discovery  of  the  changing  phases  of  Venus 
and  the  variation  of  its  apparent  diameter  during  its 
revolution  about  the  sun.  Galileo's  proof  of  the 
Copernican  theory  marked  the  downfall  of  medi- 
aevalism  and  established  astronomy  on  a  firm  foun- 
dation. But  while  his  telescope  multiplied  a  hun- 
dredfold the  number  of  visible  stars,  more  than  a 
century  elapsed  before  the  true  possibilities  of  side- 
real astronomy  were  perceived. 
[6] 


THE    NEW    HEAVENS 

STRUCTURE    OF   THE    UNIVERSE 

Sir  William  Herschel  was  the  first  astronomer  to 
make  a  serious  attack  upon  the  problem  of  the  struc- 


Fig.  4.     The  loo-inch  Hooker  telescope. 

ture  of  the  stellar  universe.  In  his  first  memoir  on 
the  "Construction  of  the  Heavens,"  read  before  the 
Royal  Society  in  1784,  he  wrote  as  follows: 


UNIVERSITY  OF  CALIFORNIA 
DEPARTMENT  OF  CIVIL   ENGINEERING 

i  .EY.  CALIFORNIA 


THE    NEW    HEAVENS 

"Hitherto  the  sidereal  heavens  have,  not  inade- 
quately for  the  purpose  designed,  been  represented 
by  the  concave  surface  of  a  sphere  in  the  centre  of 
which  the  eye  of  an  observer  might  be  supposed  to 
be  placed.  ...  In  future  we  shall  look  upon  those 
regions  into  which  we  may  now  penetrate  by  means 
of  such  large  telescopes,  as  a  naturalist  regards  a  rich 
extent  of  ground  or  chain  of  mountains  containing 
strata  variously  inclined  and  directed  as  well  as  con- 
sisting of  very  different  materials." 

On  turning  his  1 8-inch  reflecting  telescope  to  a 
part  of  the  Milky  Way  in  Orion,  he  found  its  whitish 
appearance  to  be  completely  resolved  into  small 
stars,  not  separately  seen  with  his  former  telescopes. 
"The  glorious  multitude  of  stars  of  all  possible 
sizes  that  presented  themselves  here  to  my  view  are 
truly  astonishing;  but  as  the  dazzling  brightness  of 
glittering  stars  may  easily  mislead  us  so  far  as  to 
estimate  their  number  greater  than  it  really  is,  I 
endeavored  to  ascertain  this  point  by  counting  many 
fields,  and  computing  from  a  mean  of  them,  what  a 
certain  given  portion  of  the  Milky  Way  might  con- 
tain." By  this  means,  applied  not  only  to  the  Milky 
Way  but  to  all  parts  of  the  heavens,  Herschel  deter- 
mined the  approximate  number  and  distribution  of 
all  the  stars  within  reach  of  his  instrument. 

By  comparing  many  hundred  gauges  or  counts  of 
stars  visible  in  a  field  of  about  one-quarter  of  the 
area  of  the  moon,  Herschel  found  that  the  average 
number  of  stars  increased  toward  the  great  circle 
which  most  nearly  conforms  with  the  course  of  the 
[8] 


THE    NEW    HEAVENS 

Milky  Way.  Ninety  degrees  from  this  plane,  at  the 
pole  of  the  Milky  Way,  only  four  stars,  on  the  aver- 
age, were  seen  in  the  field  of  the  telescope.  In 
approaching  the  Milky  Way  this  number  increased 


Fig.  5.     Erecting  the  polar  axis  of  the  loo-inch  telescope. 

slowly  at  first,  and  then  more  and  more  rapidly,  un- 
til it  rose  to  an  average  of  122  stars  per  field. 

These  observations  were  made  in  the  northern 
hemisphere,  and  subsequently  Sir  John  Herschel, 
using  his  father's  telescope  at  the  Cape  of  Good 
Hope,  found  an  almost  exactly  similar  increase  of 
apparent  star  density  for  the  southern  hemisphere. 
According  to  his  estimates,  the  total  number  of  stars 
in  both  hemispheres  that  could  be  seen  distinctly 
[  9] 


THE    NEW    HEAVENS 

enough  to  be  counted  in  this  telescope  would  proba- 
bly be  about  five  and  one-half  millions. 

The  Herschels  concluded  that  "the  stars  of  our 
firmament,  instead  of  being  scattered  in  all  direc- 
tions indifferently  through  space,  form  a  stratum  of 
which  the  thickness  is  small,  in  comparison  with  its 
length  and  breadth;  and  in  which  the  earth  occupies 
a  place  somewhere  about  the  middle  of  its  thickness, 
between  the  point  where  it  subdivides  into  two  prin- 
cipal laminae  inclined  at  a  small  angle  to  each  other." 
This  view  does  not  differ  essentially  from  our  modern 
conception  of  the  form  of  the  Galaxy;  but  as  the 
Herschels  were  unable  to  see  stars  fainter  than  the 
fifteenth  magnitude,  it  is  evident  that  their  conclu- 
sions apply  only  to  a  restricted  region  surrounding 
the  solar  system,  in  the  midst  of  the  enormously  ex- 
tended sidereal  universe  which  modern  instruments 
have  brought  within  our  range. 

MODERN   METHODS 

The  remarkable  progress  of  modern  astronomy 
is  mainly  due  to  two  great  instrumental  advances: 
the  rise  and  development  of  the  photographic  tele- 
scope, and  the  application  of  the  spectroscope  to  the 
study  of  celestial  objects.  These  new  and  powerful 
instruments,  supplemented  by  many  accessories 
which  have  completely  revolutionized  observatory 
equipment,  have  not  only  revealed  a  vastly  greater 
number  of  stars  and  nebulae:  they  have  also  rendered 
feasible  observations  of  a  type  formerly  regarded  as 
impossible.  The  chemical  analysis  of  a  faint  star 
[  10  1 


THE    NEW    HEAVENS 

is  now  so  easy  that  it  can  be  accomplished  in  a  very 
short  time — as  quickly,  in  fact,  as  an  equally  com- 
plex substance  can  be  analyzed  in  the  laboratory. 
The  spectroscope  also  measures  a  star's  velocity, 


Fig.  6.     Lowest  section  of  tube  of  loo-inch  telescope,  ready 
to  leave  Pasadena  for  Mount  Wilson. 


the  pressure  at  different  levels  in  its  atmosphere,  its 
approximate  temperature,  and  now,  by  a  new  and 
ingenious  method,  its  distance  from  the  earth.  It 
determines  the  velocity  of  rotation  of  the  sun  and 
of  nebulae,  the  existence  and  periods  of  orbital  revo- 
lution of  binary  stars  too  close  to  be  separated  by 
any  telescope,  the  presence  of  magnetic  fields  in  sun- 
spots,  and  the  fact  that  the  entire  sun,  like  the  earth, 
is  a  magnet. 

[  ii  1 


THE    NEW    HEAVENS 

Such  new  possibilities,  with  many  others  resulting 
from  the  application  of  physical  methods  of  the  most 
diverse  character,  have  greatly  enlarged  the  astrono- 
mer's outlook.  He  may  now  attack  two  great  prob- 
lems: (i)  The  structure  of  the  universe  and  the  mo- 
tions of  its  constituent  bodies,  and  (2)  the  evolution 
of  the  stars:  their  nature,  origin,  growth,  and  de- 
cline. These  two  problems  are  intimately  related 
and  must  be  studied  as  one.* 

If  space  permitted,  it  would  be  interesting  to  sur- 
vey the  progress  already  accomplished  by  modern 
methods  of  astronomical  research.  Hundreds  of 
millions  of  stars  have  been  photographed,  and  the 
boundaries  of  the  stellar  universe  have  been  pushed 
far  into  space,  but  have  not  been  attained.  Globu- 
lar star  clusters,  containing  tens  of  thousands  of 
stars,  are  on  so  great  a  scale  (according  to  Shapley) 
that  light,  travelling  at  the  rate  of  186,000  miles  per 
second,  may  take  500  years  to  cross  one  of  them, 
while  the  most  distant  of  these  objects  may  be  more 
than  200,000  light-years  from  the  earth.  The  spiral 
nebulae,  more  than  a  million  in  number,  are  vast 
whirling  masses  in  process  of  development,  but  we 
are  not  yet  certain  whether  they  should  be  regarded 
as  "island  universes"  or  as  subordinate  to  the  stellar 
system  which  includes  our  minute  group  of  sun  and 
planets,  the  great  star  clouds  of  the  Milky  Way, 
and  the  distant  globular  star  clusters. 

These  few  particulars  may  give  a  slight  concep- 

*  A  third  great  problem  open  to  the  astronomer,  the  study  of 
the  constitution  of  matter,  is  described  in  Chapter  III. 

t    12] 


THE    NEW    HEAVENS 

tion  of  the  scale  of  the  known  universe,  but  a  word 
must  be  added  regarding  some  of  its  most  striking 
phenomena.  The  great  majority  of  the  stars  whose 
motions  have  been  determined  belong  to  one  or  the 


Fig.  7.     Section  of  a  steel  girder  for  dome  covering  the  100- 
inch  telescope,  on  its  way  up  Mount  Wilson. 


other  of  two  great  star  streams,  but  the  part  played 
by  these  streams  in  the  sidereal  system  as  a  whole 
is  still  obscure.  The  stars  have  been  grouped  in 
classes,  presumably  in  the  order  of  their  evolutional 
development,  as  they  pass  from  the  early  state  of 
gaseous  masses,  of  low  density,  through  the  succes- 
sive stages  resulting  from  loss  of  heat  by  radiation 
and  increased  density  due  to  shrinkage.  Strangely 
[  13  ] 


THE    NEW    HEAVENS 

enough,  their  velocities  in  space  show  a  correspond- 
ing change,  increasing  as  they  grow  older  or  perhaps 
depending  upon  their  mass. 

It  is  impossible  within  these  limits  to  do  more  than 
to  give  some  indication  of  the  scope  of  the  new 
astronomy.  Enough  has  been  said,  however,  to 
assist  in  appreciating  the  increased  opportunity  for 
investigation,  and  the  nature  of  the  heavy  demands 
made  upon  the  modern  observatory.  But  before 
passing  on  to  describe  one  of  the  latest  additions  to 
the  astronomer's  instrumental  equipment,  a  word 
should  be  added  regarding  the  chief  classes  of  tele- 
scopes. 

REFRACTORS  AND  REFLECTORS 

Astronomical  telescopes  are  of  two  types:  refrac- 
tors and  reflectors.  A  refracting  telescope  consists 
of  an  object-glass  composed  of  two  or  more  lenses, 
mounted  at  the  upper  end  of  a  tube,  which  is  pointed 
at  the  celestial  object.  The  light,  after  passing 
through  the  lenses,  is  brought  to  a  focus  at  the  lower 
end  of  the  tube,  where  the  image  is  examined  visu- 
ally with  an  eyepiece,  or  photographed  upon  a  sen- 
sitive plate.  The  largest  instruments  of  this  type 
are  the  36-inch  Lick  telescope  and  the  4O-inch  re- 
fractor of  the  Yerkes  Observatory. 

Reflecting  telescopes,  which  are  particularly 
adapted  for  photographic  work,  though  also  excel- 
lent for  visual  observations,  are  very  differently  con- 
structed. No  lens  is  used.  The  telescope  tube  is 
usually  built  in  skeleton  form,  open  at  its  upper  end, 

[  14] 


THE    NEW    HEAVENS 

and  with  a  large  concave  mirror  supported  at  its 
base.     This  mirror  serves  in  place  of  a  lens.     Its 


Fig.  8.     Erecting  the  steel  building  and  revolving  dome  that 
cover  the  Hooker  telescope. 

upper  surface  is  paraboloidal  in  shape,  as  a  spherical 
surface  will  not  unite  in  a  sharp  focus  the  rays  com- 

[  15  1 


THE    NEW    HEAVENS 

ing  from  a  distant  object.  The  light  passes  through 
no  glass — a  great  advantage,  especially  for  photog- 
raphy, as  the  absorption  in  lenses  cuts  out  much  of 
the  blue  and  violet  light,  to  which  photographic 
plates  are  most  sensitive.  The  reflection  occurs  on 
the  upper  surface  of  the  mirror,  which  is  covered 
with  a  coat  of  pure  silver,  renewed  several  times  a 
year  and  always  kept  highly  burnished.  Silvered 
glass  is  better  than  metals  or  other  substances  for 
telescope  mirrors,  chiefly  because  of  the  perfection 
with  which  glass  can  be  ground  and  polished,  and 
the  ease  of  renewing  its  silvered  surface  when  tar- 
nished. 

The  great  reflectors  of  Herschel  and  Lord  Rosse, 
which  were  provided  with  mirrors  of  speculum 
metal,  were  far  inferior  to  much  smaller  telescopes 
of  the  present  day.  With  these  instruments  the 
star  images  were  watched  as  they  were  carried 
through  the  field  of  view  by  the  earth's  rotation,  or 
kept  roughly  in  place  by  moving  the  telescope  with 
ropes  or  chains.  Photographic  plates,  which  reveal 
invisible  stars  and  nebulae  when  exposed  for  hours 
in  modern  instruments,  were  not  then  available. 
In  any  case  they  could  not  have  been  used,  in  the 
absence  of  the  perfect  mechanism  required  to  keep 
the  star  images  accurately  fixed  in  place  upon  the 
sensitive  film. 

It  would  be  interesting  to  trace  the  long  contest 
for  supremacy  between  refracting  and  reflecting  tele- 
scopes, each  of  which,  at  certain  stages  in  its  develop- 
ment, appeared  to  be  unrivalled.  In  modern  ob- 
[  16  ] 


THE    NEW    HEAVENS 

servatories  both  types  are  used,  each  for  the  purpose 
for  which  it  is  best  adapted.  For  the  photography 
of  nebulae  and  the  study  of  the  fainter  stars,  the 
reflector  has  special  advantages,  illustrated  by  the 
work  of  such  instruments  as  the  Crossley  and  Mills 


Fig.  9.     Building  and  revolving  dome,  100  feet  in  diameter, 

covering  the  loo-inch  Hooker  telescope. 
Photographed  from  the  summit  of  the  I5o-foot-tower  telescope. 

reflectors  of  the  Lick  Observatory;  the  great  72-inch 
reflector,  recently  brought  into  effective  service  at 
the  Dominion  Observatory  in  Canada;  and  the  60- 
inch  and  loo-inch  reflectors  of  the  Mount  Wilson 
Observatory. 

The  unaided  eye,  with  an  available  area  of  one- 
twentieth  of  a  square  inch,  permits  us  to  see  stars  of 

1 17] 


THE    NEW    HEAVENS 

the  sixth  magnitude.  HerscheFs  1 8-inch  reflector, 
with  an  area  5,000  times  as  great,  rendered  visible 
stars  of  the  fifteenth  magnitude.  The  6o-inch  reflec- 
tor, with  an  area  57,600  times  that  of  the  eye,  re- 
veals stars  of  the  eighteenth  magnitude,  while  to 
reach  stars  of  about  the  twentieth  magnitude,  pho- 
tographic exposures  of  four  or  five  hours  suffice  with 
this  instrument. 

Every  gain  of  a  magnitude  means  a  great  gain  in 
the  number  of  stars  rendered  visible.  Stars  of  the 
second  magnitude  are  3.4  times  as  numerous  as 
those  of  the  first,  those  of  the  eighth  magnitude  are 
three  times  as  numerous  as  those  of  the  seventh, 
while  the  sixteenth  magnitude  stars  are  only  1.7  as 
numerous  as  those  of  the  fifteenth  magnitude.  This 
steadily  decreasing  ratio  is  probably  due  to  an  actual 
thinning  out  of  the  stars  toward  the  boundaries  of 
the  stellar  universe,  as  the  most  exhaustive  tests 
have  failed  to  give  any  evidence  of  absorption  of 
light  in  its  passage  through  space.  But  in  spite  of 
this  decrease,  the  gain  of  a  single  additional  magni- 
tude may  mean  the  addition  of  many  millions  of 
stars  to  the  total  of  those  already  shown  by  the  60- 
inch  reflector.  Here  is  one  of  the  chief  sources  of 
interest  in  the  possibilities  of  a  loo-inch  reflecting 
telescope. 

100-INCH    TELESCOPE 

In  1906  the  late  John  D.  Hooker,  of  Los  Angeles, 
gave  the  Carnegie  Institution  of  Washington  a  sum 
sufficient  to  construct  a  telescope  mirror  100  inches 
[  18  ] 


THE    NEW    HEAVENS 

in  diameter,  and  thus  large  enough  to  collect  160,000 
times  the  light  received  by  the  eye.  (Fig.  10.)  The 
casting  and  annealing  of  a  suitable  glass  disk,  101 
inches  in  diameter  and  13  inches  thick,  weighing 
four  and  one-half  tons,  was  a  most  difficult  opera- 


Fig.  10.     One-hundred-inch  mirror,  just  silvered,  rising  out  of  the 

silvering-room  in  pier  before  attachment  to  lower  end  of 

telescope  tube.     (Seen  above.) 

tion,  finally  accomplished  by  a  great  French  glass 
company  at  their  factory  in  the  Forest  of  St.  Go- 
bain.  A  special  optical  laboratory  was  erected  at 
the  Pasadena  headquarters  of  the  Mount  Wilson 
Observatory,  and  here  the  long  task  of  grinding, 
figuring,  and  testing  the  mirror  was  successfully  car- 
ried out  by  the  observatory  opticians.  This  opera- 

[  19  1 


THE    NEW    HEAVENS 

tion,  which  is  one  of  great  delicacy,  required  years 
for  its  completion.  Meanwhile  the  building,  dome, 
and  mounting  for  the  telescope  were  designed  by 
members  of  the  observatory  staff,  and  the  working 
drawings  were  prepared.  An  opportune  addition  by 
Mr.  Carnegie  to  the  endowment  of  the  Carnegie 
Institution  of  Washington,  of  which  the  observatory 
is  a  branch,  permitted  the  necessary  appropriations 
to  be  made  for  the  completion  and  erection  of  the 
telescope.  Though  delayed  by  the  war,  during 
which  the  mechanical  and  optical  facilities  of  the 
observatory  shops  were  utilized  for  military  and 
naval  purposes,  the  telescope  is  now  in  regular  use 
on  Mount  Wilson. 

The  instrument  is  mounted  on  a  massive  pier  of 
reinforced  concrete,  33  feet  high  and  52  feet  in  di- 
ameter at  the  top.  A  solid  wall  extends  south  from 
this  pier  a  distance  of  50  feet,  on  the  west  side  of 
which  a  very  powerful  spectrograph,  for  photo- 
graphing the  spectra  of  the  brightest  stars,  will  be 
mounted.  Within  the  pier  are  a  photographic  dark 
room,  a  room  for  silvering  the  large  mirror  (which 
can  be  lowered  into  the  pier),  and  the  clock-room, 
where  stands  the  powerful  driving-clock,  with  which 
the  telescope  is  caused  to  follow  the  apparent  motion 
of  the  stars.  (Fig.  n.) 

The  telescope  mounting  is  of  the  English  type,  in 
which  the  telescope  tube  is  supported  by  the  declina- 
tion trunnions  between  the  arms  of  the  polar  axis, 
built  in  the  form  of  a  rectangular  yoke  carried  by 
bearings  on  massive  pedestals  to  the  north  and  south. 

r  20 1 


THE    NEW    HEAVENS 

These  bearings  must  be  aligned  exactly  parallel  to 
the  axis  of  the  earth,  and  must  support  the  polar 
axis  so  freely  that  it  can  be  rotated  with  perfect  pre- 
cision by  the  driving-clock,  which  turns  a  worm- 


Fig,  ii.     The  driving-clock  and  worm-gear  that  cause  the  100- 
inch  Hooker  telescope  to  follow  the  stars. 

wheel  17  feet  in  diameter,  clamped  to  the  lower  end 
of  the  axis.  As  this  motion  must  be  sufficiently  uni- 
form to  counteract  exactly  the  rotation  of  the  earth 
on  its  axis,  and  thus  to  maintain  the  star  images 
accurately  in  position  in  the  field  of  view,  the  great- 
est care  had  to  be  taken  in  the  construction  of  the 
driving-clock  and  in  the  spacing  and  cutting  of  the 
teeth  in  the  large  worm-wheel.  Here,  as  in  the  case 

[   21    ] 


THE    NEW    HEAVENS 

of  all  of  the  more  refined  parts  of  the  instrument, 
the  work  was  done  by  skilled  machinists  in  the  ob- 
servatory shops  in  Pasadena  or  on  Mount  Wilson 


Fig.  12.     Large  irregular  nebula  and  star  cluster  in  Sagittarius 
(Duncan). 

Photographed  with  the  6o-inch  telescope. 

after  the  assembling  of  the  telescope.  The  massive 
sections  of  the  instrument,  some  of  which  weigh  as 
much  as  ten  tons  each,  were  constructed  at  Quincy, 
Mass.,  where  machinery  sufficiently  large  to  build 
battleships  was  available.  They  were  then  shipped 
to  California,  and  transported  to  the  summit  of 

[22] 


THE    NEW    HEAVENS 

Mount  Wilson  over  a  road  built  for  this  purpose 
by  the  construction  division  of  the  observatory, 
which  also  built  the  pier  on  which  the  telescope 


Fig.  13.     Faint  spiral  nebula  in  the  constellation  of  the 

Hunting  Dogs  (Pease). 
Photographed  with  the  6o-inch  telescope. 

stands,  and  erected  the  steel  building  and  dome  that 
cover  it. 

The  parts  of  the  telescope  which  are  moved  by 
the  driving-clock  weigh  about  100  tons,  and  it  was 
necessary  to  provide  means  of  reducing  the  great 
friction  on  the  bearings  of  the  polar  axis.  To  ac- 
complish this,  large  hollow  steel  cylinders,  floating 
in  mercury  held  in  cast-iron  tanks,  were  provided 
at  the  upper  and  lower  ends  of  the  polar  axis.  Al- 
[  23  ] 


THE    NEW    HEAVENS 

most  the  entire  weight  of  the  instrument  is  thus 
floated  in  mercury,  and  in  this  way  the  friction  is  so 
greatly  reduced  that  the  driving-clock  moves  the 
instrument  with  perfect  ease  and  smoothness. 

The  loo-inch  mirror  rests  at  the  bottom  of  the 
telescope  tube  on  a  special  support  system,  so  de- 
signed as  to  prevent  any  bending  of  the  glass  under 
its  own  weight.  Electric  motors,  forty  in  number, 
are  provided  to  move  the  telescope  rapidly  or  slowly 
in  right  ascension  (east  or  west)  and  in  declination 
(north  or  south),  for  focussing  the  mirrors,  and  for 
many  other  purposes.  They  are  also  used  for  ro- 
tating the  dome,  100  feet  in  diameter,  under  which 
the  telescope  is  mounted,  and  for  opening  the 
shutter,  20  feet  wide,  through  which  the  observa- 
tions are  made. 

A  telescope  of  this  kind  can  be  used  in  several 
different  ways.  The  loo-inch  mirror  has  a  focal 
length  of  about  42  feet,  and  in  one  of  the  arrange- 
ments of  the  instrument,  the  photographic  plate  is 
mounted  at  the  centre  of  the  telescope  tube  near  its 
upper  end,  where  it  receives  directly  the  image 
formed  by  the  large  mirror.  In  another  arrange- 
ment, a  silvered  glass  mirror,  with  plane  surface,  is 
supported  near  the  upper  end  of  the  tube  at  an  angle 
of  45°,  so  as  to  form  the  image  at  the  side  of  the 
tube,  where  the  photographic  plate  can  be  placed. 
In  this  case,  the  observer  stands  on  a  platform, 
which  is  moved  up  and  down  by  electric  motors  in 
front  of  the  opening  in  the  dome  through  which  the 
observations  are  made. 

[  24  ] 


THE    NEW    HEAVENS 

Other  arrangements  of  the  telescope,  for  which 
auxiliary  convex  mirrors  carried  near  the  upper  end 
of  the  tube  are  required,  permit  the  image  to  be 
photographed  at  the  side  of  the  tube  near  its  lower 


Fig.  14.     Spiral  nebula  in  Andromeda,  seen  edge  on  (Ritchey). 
Photographed  with  the  6o-inch  telescope. 

end,  either  with  or  without  a  spectrograph;  or  with 
a  very  powerful  spectrograph  mounted  within  a  con- 
stant-temperature chamber  south  of  the  telescope 
pier.  In  this  last  case,  the  light  of  a  star  is  so  re- 
flected by  auxiliary  mirrors  that  it  passes  down 
through  a  hole  in  the  south  end  of  the  polar  axis  and 
brings  the  star  to  a  focus  on  the  slit  of  the  fixed 
spectrograph. 


THE    NEW    HEAVENS 


ATMOSPHERIC    LIMITATIONS 

The  huge  dimensions  of  such  a  powerful  engine 
of  research  as  the  Hooker  telescope  are  not  in  them- 
selves a  source  of  satisfaction  to  the  astronomer, 
for  they  involve  a  decided  increase  in  the  labor  of 
observation  and  entail  very  heavy  expense,  justifi- 
able only  in  case  important  results,  beyond  the 
reach  of  other  instruments,  can  be  secured.  The 
construction  of  a  telescope  of  these  dimensions  was 
necessarily  an  experiment,  for  it  was  by  no  means 
certain,  after  the  optical  and  mechanical  difficulties 
had  been  overcome,  that  even  the  favorable  atmos- 
phere of  California  would  be  sufficiently  tranquil  to 
permit  sharply  defined  celestial  images  to  be  ob- 
tained with  so  large  an  aperture.  It  is  therefore 
important  to  learn  what  the  telescope  will  actually 
accomplish  under  customary  observing  conditions. 

Fortunately  we  are  able  to  measure  the  perform- 
ance of  the  instrument  with  certainty.  Close  be- 
side it  on  Mount  Wilson  stands  the  6o-inch  reflector, 
of  similar  type,  erected  in  1908.  The  two  telescopes 
can  thus  be  rigorously  compared  under  identical 
atmospheric  conditions. 

The  large  mirror  of  the  loo-inch  telescope  has 
an  area  about  2.8  times  that  of  the  6o-inch,  and 
therefore  receives  nearly  three  times  as  much  light 
from  a  star.  Under  atmospheric  conditions  perfect 
enough  to  allow  all  of  this  light  to  be  concentrated 
in  a  point,  it  should  be  capable  of  recording  on  a 
photographic  plate,  with  a  given  exposure,  stars 
[26! 


THE    NEW    HEAVENS 

about  one  magnitude  fainter  than  the  faintest  stars 
within  reach  of  the  6o-inch.  The  increased  focal 
length,  permitting  such  objects  as  the  moon  to  be 
photographed  on  a  larger  scale,  should  also  re- 
veal smaller  details  of  structure  and  render  pos- 
sible higher  accuracy  of  measurement.  Finally,  the 
greater  theoretical  resolving  power  of  the  larger 
aperture,  providing  it  can  be  utilized,  should  permit 
the  separation  of  the  members  of  close  double  stars 
beyond  the  range  of  the  smaller  instrument. 

CRITICAL    TESTS 

The  many  tests  already  made  indicate  that  the 
advantages  expected  of  the  new  telescope  will  be 
realized  in  practice.  The  increased  light-gathering 
power  will  mean  the  addition  of  many  millions  of 
stars  to  those  already  known.  Spectroscopic  ob- 
servations now  in  regular  progress  have  carried  the 
range  of  these  investigations  far  beyond  the  possi- 
bilities of  the  6o-inch  telescope.  A  great  class  of 
red  stars,  for  example,  almost  all  the  members  of 
which  were  inaccessible  to  the  6o-inch,  are  now  being 
made  the  subject  of  special  study.  And  in  other 
fields  of  research  equal  advantages  have  been  gained. 

The  increase  in  the  scale  of  the  images  over  those 
given  by  the  6o-inch  telescope  is  illustrated  by  two 
photographs  of  the  Ring  Nebula  in  Lyra,  reproduced 
in  Fig.  1 8.  The  Great  Nebula  in  Orion,  photo- 
graphed with  the  loo-inch  telescope  with  a  com- 
paratively short  exposure,  sufficient  to  bring  out 
the  brighter  regions,  is  reproduced  in  Fig.  2.  It  is 
[27] 


Fig.  15.     Photograph  of  the  moon  made  on  September  15,  1919, 
with  the  loo-inch  Hooker  telescope  (Pease). 

The  ring-like  formations  are  the  so-called  craters,  most  of  them  far  larger  than 
anything  similar  on  the  earth.  That  in  the  lower  left  corner  with  an  isolated 
mountain  in  the  centre  is  Albategnius,  sixty-four  miles  in  diameter.  Peaks 
in  the  ring  rise  to  a  height  of  fifteen  thousand  feet  above  the  central  plain. 
Note  the  long  sunset  shadows  cast  by  the  mountains  on  the  left.  The  level 
region  below  on  the  right  is  an  extensive  plain,  the  Mare  Nubium. 


Fig.  16.     Photograph  of  the  moon  made  on  September  15,   1919, 
with  the  loo-inch  Hooker  telescope  (Pease). 

The  mountains  above  and  to  the  left  are  the  lunar  Apennines;  those  on  the  left 
just  below  the  centre  are  the  Alps.  Both  ranges  include  peaks  from  fifteen 
thousand  to  twenty  thousand  feet  in  height.  In  the  upper  right  corner  is 
Copernicus,  about  fifty  miles  in  diameter.  The  largest  of  the  conspicuous 
group  of  three  just  below  the  Apennines  is  Archimedes  and  at  the  lower  end 
of  the  Alps  is  Plato.  Note  the  long  sunset  shadows  cast  by  the  isolated 
peaks  on  the  left.  The  central  portion  of  the  picture  is  a  vast  plain,  the 
Mare  Imbrium. 


THE    NEW    HEAVENS 

interesting  to  compare  this  picture  with  the  small- 
scale  image  of  the  same  nebula  shown  in  Fig.  I. 

The  sharpness  of  the  images  given  by  the  new 
telescope  may  be  illustrated  by  some  recent  photo- 
graphs of  the  moon,  obtained  with  an  equivalent 
focal  length  of  134  feet.  In  Fig.  15  is  shown  a 
rugged  region  of  the  moon,  containing  many  ring- 
like  mountains  or  craters.  Fig.  16  shows  the  great 
arc  of  the  lunar  Apennines  (above)  and  the  Alps 
(below),  to  the  left  of  the  broad  plain  of  the  Mare 
Imbrium.  The  starlike  points  along  the  moon's 
terminator,  which  separates  the  dark  area  from  the 
region  upon  which  the  sun  (on  the  right)  shines,  are 
the  mountain  peaks,  about  to  disappear  at  sunset. 
The  long  shadows  cast  by  the  mountains  just  with- 
in the  illuminated  area  are  plainly  seen.  Some  of 
the  peaks  of  the  lunar  Apennines  attain  a  height  of 
20,000  feet. 

In  less  powerful  telescopes  the  stars  at  the  centre 
of  the  great  globular  clusters  are  so  closely  crowded 
together  that  they  cannot  be  studied  separately  with 
the  spectrograph.  Moreover,  most  of  them  are  much 
too  faint  for  examination  with  this  instrument.  At 
the  134-foot  focus  the  loo-inch  telescope  gives  a 
large-scale  image  of  such  clusters,  and  permits  the 
spectra  of  stars  as  faint  as  the  fifteenth  magnitude 
to  be  separately  photographed. 

CLOSE    DOUBLE    STARS 

A  remarkable  use  of  the  loo-inch  telescope,  which 
permits  its  full  theoretical  resolving  power  to  be  not 
[30] 


THE    NEW    HEAVENS 

merely  attained  but  to  be  doubled,  has  been  made 
possible  by  the  first  application  of  Michelson's  inter- 


Fig.  17.     Hubble's  Variable  Nebula.    One  of  the  few  nebulae 
known  to  vary  in  brightness  and  form. 

Photographed  with  the  loo-inch  telescope  (Hubble). 

ference  method  to  the  measurement  of  very  close 
double  stars.  When  employing  this,  the  loo-inch 
mirror  is  completely  covered,  except  for  two  slits. 

[31  1 


THE    NEW    HEAVENS 

Beams  of  light  from  a  star,  entering  by  the  slits, 
unite  at  the  focus  of  the  telescope,  where  the  image 
is  examined  by  an  eyepiece  magnifying  about  five 
thousand  diameters.  Across  the  enlarged  star  image 
a  series  of  fine,  sharp  fringes  is  seen,  even  when  the 
atmospheric  conditions  are  poor.  If  the  star  is 


Fig.  1 8.     Ring  Nebula  in  Lyra,  photographed  with  the  6o-inch 

(Ritchey)  and  loo-inch  (Duncan)  telescopes. 
Showing  the  increased  scale  of  the  images  given  by  the  larger  instrument. 

single  the  fringes  remain  visible,  whatever  the  dis- 
tance between  the  slits.  But  in  the  case  of  a  star 
like  Capella,  previously  inferred  to  be  double  from 
the  periodic  displacement  of  the  lines  in  its  spec- 
trum, but  with  components  too  close  together  to  be 
distinguished  separately,  the  fringes  behave  differ- 
ently. As  the  slits  are  moved  apart  a  point  is 
reached  where  the  fringes  completely  disappear, 
only  to  reappear  as  the  separation  is  continued. 
This  effect  is  obtained  when  the  slits  are  at  right 
[  32] 


THE    NEW    HEAVENS 

angles  to  the  line  joining  the  two  stars  of  the  pair, 
found  by  this  method  to  be  0.0418  of  a  second  of  arc 
apart  (on  December  30,  1919).  Subsequent  mea- 
sures, of  far  greater  precision  than  those  obtainable 
by  other  methods  in  the  case  of  easily  separated 
double  stars,  show  the  rapid  orbital  motion  of  the 
components  of  the  system.  This  device  will  be  ap- 
plied to  other  close  binaries,  hitherto  beyond  the 
reach  of  measurement. 

Without  entering  into  further  details  of  the  tests, 
it  is  evident  that  the  new  telescope  will  afford 
boundless  possibilities  for  the  study  of  the  stellar 
universe.*  The  structure  and  extent  of  the  galactic 
system,  and  the  motions  of  the  stars  comprising  it; 
the  distribution,  distances,  and  dimensions  of  the 
spiral  nebulae,  their  motions,  rotation,  and  mode  of 
development;  the  origin  of  the  stars  and  the  succes- 
sive stages  in  their  life  history:  these  are  some  of  the 
great  questions  which  the  new  telescope  must  help 
to  answer.  In  such  an  embarrassment  of  riches  the 
chief  difficulty  is  to  withstand  the  temptation  toward 
scattering  of  effort,  and  to  form  an  observing  pro- 
gramme directed  toward  the  solution  of  crucial 
problems  rather  than  the  accumulation  of  vast 
stores  of  miscellaneous  data.  This  programme  will 
be  supplemented  by  an  extensive  study  of  the  sun, 
the  only  star  near  enough  the  earth  to  be  examined 
in  detail,  and  by  a  series  of  laboratory  investigations 

*  It  is  not  adapted  for  work  on  the  sun,  as  the  mirrors  would  be 
distorted  by  its  heat.  Three  other  telescopes,  especially  designed 
for  solar  observations,  are  in  use  on  Mount  Wilson. 

[33 1 


THE    NEW    HEAVENS 

involving  the  experimental  imitation  of  solar  and 
stellar  conditions,  thus  aiding  in  the  interpretation 
of  celestial  phenomena. 


[34] 


CHAPTER  II 
GIANT  STARS 

OUR  ancestral  sun,  as  pictured  by  Laplace,  origi- 
nally extended  in  a  state  of  luminous  vapor  beyond 
the  boundaries  of  the  solar  system.  Rotating  upon 
its  axis,  it  slowly  contracted  through  loss  of  heat  by 
radiation,  leaving  behind  it  portions  of  its  mass, 
which  condensed  to  form  the  planets.  Still  gaseous, 
though  now  denser  than  water,  it  continues  to  pour 
out  the  heat  on  which  our  existence  depends,  as  it 
shrinks  imperceptibly  toward  its  ultimate  condition 
of  a  cold  and  darkened  globe. 

Laplace's  hypothesis  has  been  subjected  in  recent 
years  to  much  criticism,  and  there  is  good  reason  to 
doubt  whether  his  description  of  the  mode  of  evolu- 
tion of  our  solar  system  is  correct  in  every  particular. 
All  critics  agree,  however,  that  the  sun  was  once 
enormously  larger  than  it  now  is,  and  that  the  plan- 
ets originally  formed  part  of  its  distended  mass. 

Even  in  its  present  diminished  state,  the  sun  is 
huge  beyond  easy  conception.  Our  own  earth, 
though  so  minute  a  fragment  of  the  primeval  sun, 
is  nevertheless  so  large  that  some  parts  of  its  sur- 
face have  not  yet  been  explored.  Seen  beside  the 

[  35  1 


THE    NEW   HEAVENS 

sun,  by  an  observer  on  one  of  the  planets,  the  earth 
would  appear  as  an  insignificant  speck,  which  could 
be  swallowed  with  ease  by  the  whirling  vortex  of  a 
sun-spot.  If  the  sun  were  hollow,  with  the  earth 


Fig.  19.     Gaseous  prominence  at  the  sun's  limb,  140,000  miles 
high  (Ellerman). 

Photographed  with  the  spectroheliograph,  using  the  light  emitted  by  glowing 
calcium  vapor.  The  comparative  size  of  the  earth  is  indicated  by  the 
white  circle. 

at  its  centre,  the  moon,  though  240,000  miles  from 
us,  would  have  room  and  to  spare  in  which  to  de- 
scribe its  orbit,  for  the  sun  is  865,000  miles  in 
diameter,  so  that  its  volume  is  more  than  a  million 
times  that  of  the  earth. 

But  what  of  the  stars,  proved  by  the  spectroscope 
to  be  self-luminous,  intensely  hot,  and  formed  of  the 
[  36] 


GIANT    STARS 

same  chemical  elements  that  constitute  the  sun  and 
the  earth  ?  Are  they  comparable  in  size  with  the 
sun  ?  Do  they  occur  in  all  stages  of  development, 


Fig.   20.     The  sun,   865,000  miles   in  diameter,   from  a  direct 
photograph  showing  many  sun-spots  (Whitney) 

The  small  black  disk  in  the  centre  represents  the  comparative  size  of  the  earth, 
while  the  circle  surrounding  it  corresponds  in  diameter  to  the  orbit  of  the 
moon. 


from  infancy  to  old  age  ?  And  if  such  stages  can  be 
detected,  do  they  afford  indications  of  the  gradual 
diminution  in  volume  which  Laplace  imagined  the 
sun  to  experience  ? 

[37  I 


THE    NEW    HEAVENS 

STAR    IMAGES 

Prior  to  the  application  of  the  powerful  new  en- 
gine:,of  research  described  in  this  article  we  have  had 
no  means  of  measuring  the  diameters  of  the  stars. 
We  have  measured  their  distances  and  their  mo- 
tions, determined  their  chemical  composition,  and 
obtained  undeniable  evidence  of  progressive  devel- 
opment, but  even  in  the  most  powerful  telescopes 
their  images  are  so  minute  that  they  appear  as  points 
rather  than  as  disks.  In  fact,  the  larger  the  tele- 
scope and  the  more  perfect  the  atmospheric  condi- 
tions at  the  observer's  command,  the  smaller  do 
these  images  appear.  On  the  photographic  plate, 
it  is  true,  the  stars  are  recorded  as  measurable 
disks,  but  these  are  due  to  the  spreading  of  the 
light  from  their  bright  point-like  images,  and  their 
diameters  increase  as  the  exposure  time  is  prolonged. 
From  the  images  of  the  brighter  stars  rays  of  light 
project  in  straight  lines,  but  these  also  are  instru- 
mental phenomena,  due  to  diffraction  of  light  by 
the  steel  bars  that  support  the  small  mirror  in  the 
tube  of  reflecting  telescopes.  In  a  word,  the  stars 
are  so  remote  that  the  largest  and  most  perfect 
telescopes  show  them  only  as  extremely  minute 
needle-points  of  light,  without  any  trace  of  their 
true  disks. 

How,  then,  may  we  hope  to  measure  their  diame- 
ters ?  By  using,  as  the  man  of  science  must  so  often 
do,  indirect  means  when  the  direct  attack  fails. 
Most  of  the  remarkable  progress  of  astronomy  dur- 
[38  ] 


GIANT    STARS 

ing  the  last  quarter-century  has  resulted  from  the 
application  of  new  and  ingenious  devices  borrowed 
from  the  physicist.  These  have  multiplied  to  such 
a  degree  that  some  of  our  observatories  are  literally 


Fig.  21.     Great  sun-spot  group,  August  8,  1917  (Whitney). 
The  disk  in  the  corner  represents  the  comparative  size  of  the  earth. 

physical  laboratories,  in  which  the  sun  and  stars  are 
examined  by  powerful  spectroscopes  and  other  opti- 
cal instruments  that  have  recently  advanced  our 
knowledge  of  physics  by  leaps  and  bounds.  In  the 
present  case  we  are  indebted  for  our  star-measuring 
device  to  the  distinguished  physicist  Professor  Al- 
bert A.  Michelson,  who  has  contributed  a  long  array 

[39] 


THE    NEW    HEAVENS 

of  novel   apparatus   and    methods   to   physics   and 
astronomy. 

THE   INTERFEROMETER 

The  instrument  in  question,  known  as  the  inter- 
ferometer, had  previously  yielded  a  remarkable  se- 
ries of  results  when  applied  in  its  various  forms  to 
the  solution  of  fundamental  problems.  To  mention 
only  a  few  of  those  that  have  helped  to  establish 
Michelson's  fame,  we  may  recall  that  our  exact 
knowledge  of  the  length  of  the  international  metre 
at  Sevres,  the  world's  standard  of  measurement,  was 
obtained  by  him  with  an  interferometer  in  terms  of 
the  invariable  length  of  light-waves.  A  different 
form  of  interferometer  has  more  recently  enabled 
him  to  measure  the  minute  tides  within  the  solid 
body  of  the  earth — not  the  great  tides  of  the  ocean, 
but  the  slight  deformations  of  the  earth's  body, 
which  is  as  rigid  as  steel,  that  are  caused  by  the 
varying  attractions  of  the  sun  and  moon.  Finally, 
to  mention  only  one  more  case,  it  was  the  Michelson- 
Morley  experiment,  made  years  ago  with  still  an- 
other form  of  interferometer,  that  yielded  the  basic 
idea  from  which  the  theory  of  relativity  was  devel- 
oped by  Lorentz  and  Einstein. 

The  history  of  the  method  of  measuring  star 
diameters  is  a  very  curious  one,  showing  how  the 
most  promising  opportunities  for  scientific  progress 
may  lie  unused  for  decades.  The  fundamental 
principle  of  the  device  was  first  suggested  by  the 
great  French  physicist  Fizeau  in  1868.  In  1874  the 
[40] 


GIANT    STARS 

theory  was  developed  by  the  French  astronomer 
Stephan,  who  observed  interference  fringes  given  by 
a  large  number  of  stars,  and  rightly  concluded  that 


Fig.  22.     Photograph  of  the  hydrogen  atmosphere  of  the  sun 
(Ellerman). 

Made  with  the  spectroheliograph,  showing  the  immense  vortices,  or  whirling 
storms  like  tornadoes,  that  centre  in  sun-spots.  The  comparative  size  of 
the  earth  is  shown  by  the  white  circle  traced  on  the  largest  sun-spot. 

their  angular  diameters  must  be  much  smaller  than 
o.  1 58  of  a  second  of  arc,  the  smallest  measurable  with 
his  instrument.  In  1890  Michelson,  unaware  of 
the  earlier  work,  published  in  the  Philosophical 
Magazine  a  complete  description  of  an  interferometer 
[  4i  ] 


THE    NEW    HEAVENS 

capable  of  determining  with  surprising  accuracy  the 
distance  between  the  components  of  double  stars  so 
close  together  that  no  telescope  can  separate  them. 
He  also  showed  how  the  same  principle  could  be 
applied  to  the  measurement  of  star  diameters  if  a 
sufficiently  large  interferometer  could  be  built  for 
this  purpose,  and  developed  the  theory  much  more 
completely  than  Stephan  had  done.  A  year  later 
he  measured  the  diameters  of  Jupiter's  satellites  by 
this  means  at  the  Lick  Observatory.  But  nearly 
thirty  years  elapsed  before  the  next  step  was  taken. 
Two  causes  have  doubtless  contributed  to  this  de- 
lay. Both  theory  and  experiment  have  demon- 
strated the  extreme  sensitiveness  of  the  "interfer- 
ence fringes,"  on  the  observation  of  which  the 
method  depends,  and  it  was  generally  supposed  by 
astronomers  that  disturbances  in  the  earth's  atmos- 
phere would  prevent  them  from  being  clearly  seen 
with  large  telescopes.  Furthermore,  a  very  large 
interferometer,  too  large  to  be  carried  by  any  exist- 
ing telescope,  was  required  for  the  star-diameter 
work,  though  close  double  stars  could  have  been 
easily  studied  by  this  device  with  several  of  the  large 
telescopes  of  the  early  nineties.  But  whatever  the 
reasons,  a  powerful  method  of  research  lay  unused. 
The  approaching  completion  of  the  loo-inch  tele- 
scope of  the  Mount  Wilson  Observatory  led  me  to 
suggest  to  Professor  Michelson,  before  the  United 
States  entered  the  war,  that  the  method  be  thor- 
oughly tested  under  the  favorable  atmospheric  con- 
ditions of  Southern  California.  He  was  at  that 
[42] 


GIANT    STARS 

time  at  work  on  a  special  form  of  interferometer, 
designed  to  determine  whether  atmospheric  dis- 
turbances could  be  disregarded  in  planning  large- 
scale  experiments.  But  the  war  intervened,  and 
all  of  our  efforts  were  concentrated  for  two  years  on 
the  solution  of  war  problems.*  In  1919,  as  soon  as 
the  loo-inch  telescope  had  been  completed  and 
tested,  the  work  was  resumed  on  Mount  Wilson. 

A    LABORATORY    EXPERIMENT 

The  principle  of  the  method  can  be  most  readily 
seen  by  the  aid  of  an  experiment  which  any  one  can 
easily  perform  for  himself  with  simple  apparatus. 
Make  a  narrow  slit,  a  few  thousandths  of  an  inch  in 
width,  in  a  sheet  of  black  paper,  and  support  it  verti- 
cally before  a  brilliant  source  of  light.  Observe 
this  from  a  distance  of  40  or  50  feet  with  a  small 
telescope  magnifying  about  30  diameters.  The 
object-glass  of  the  telescope  should  be  covered  with 
an  opaque  cap,  pierced  by  two  circular  holes  about 
one-eighth  of  an  inch  in  diameter  and  half  an  inch 
apart.  The  holes  should  be  on  opposite  sides  of  the 
centre  of  the  object-glass  and  equidistant  from  it, 
and  the  line  joining  the  holes  should  be  horizontal. 
When  this  cap  is  removed  the  slit  appears  as  a 
narrow  vertical  band  with  much  fainter  bands  on 
both  sides  of  it.  With  the  cap  in  place,  the  central 
bright  band  appears  to  be  ruled  with  narrow  vertical 

*  Professor  Michelson's  most  important  contribution  during 
the  war  period  was  a  new  and  very  efficient  form  of  range-finder, 
adopted  for  use  by  the  U.  S.  Navy. 

[43   1 


THE    NEW    HEAVENS 

lines  or  fringes  produced  by  the  "interference"*  of 
the  two  pencils  of  light  coming  through  different 
parts  of  the  object-glass  from  the  distant  slit. 
Cover  one  of  the  holes,  and  the  fringes  instantly  dis- 
appear. Their  production  requires  the  joint  effect 
of  the  two  light-pencils. 

Now  suppose  the  two  holes  over  the  object-glass 
to  be  in  movable  plates,  so  that  their  distance  apart 
can  be  varied.  As  they  are  gradually  separated  the 
narrow  vertical  fringes  become  less  and  less  distinct, 
and  finally  vanish  completely.  Measure  the  dis- 
tance between  the  holes  and  divide  this  by  the  wave- 
length of  light,  which  we  may  call  ^-Q^OTF  of  an  inch. 
The  result  is  the  angular  width  of  the  distant  slit. 
Knowing  the  distance  of  the  slit,  we  can  at  once 
calculate  its  linear  width.  If  for  the  slit  we  substi- 
tute a  minute  circular  hole,  the  method  of  measure- 
ment remains  the  same,  but  the  angular  diameter  as 
calculated  above  must  be  multiplied  by  i.22.f 

To  measure  the  diameter  of  a  star  we  proceed  in 
a  similar  way,  but,  as  the  angle  it  subtends  is  so 
small,  we  must  use  a  very  large  telescope,  for  the 
smaller  the  angle  the  farther  apart  must  be  the  two 
holes  over  the  object-glass  (or  the  mirror,  in  case  a 
reflecting  telescope  is  employed).  In  fact,  when  the 
holes  are  moved  apart  to  the  full  aperture  of  the 

*  For  an  explanation  of  the  phenomena  of  interference,  see  any 
encyclopaedia  or  book  on  physics. 

t  More  complete  details  may  be  found  in  Michelson's  Lowell 
Lectures  on  "Light-Waves  and  Their  Uses,"  University  of 
Chicago  Press,  1907. 

[  44  1 


GIANT    STARS 

loo-inch  Hooker  telescope,  the  interference  fringes 
are  still  visible  even  with  the  star  Betelgeuse,  though 
its  angular  diameter  is  perhaps  as  great  as  that  of 
any  other  star.  Thus,  we  must  build  an  attach- 


Fig.  23.     Diagram  showing  outline  of  the  loo-inch  Hooker  tele- 
scope, and  path  of  the  two  pencils  of  light  from  a  star  when 
under  observation  with  the  2O-foot  Michelson  interferometer. 
A  photograph  of  the  interferometer  is  shown  in  Fig.  24. 


ment  for  the  telescope,  so  arranged  as  to  permit  us 
to  move  the  openings  still  farther  apart. 

THE    20-FOOT    INSTRUMENT 

The  20-foot  interferometer  designed  by  Messrs. 
Michelson  and  Pease,  and  constructed  in  the  Mount 
Wilson  Observatory  instrument-shop,  is  shown  in 
the  diagram  (Fig.  23)  and  in  a  photograph  of  the 

[45 1 


THE    NEW    HEAVENS 

upper  end  of  the  skeleton  tube  of  the  telescope 
(Fig.  24).  The  light  from  the  star  is  received  by  two 
flat  mirrors  (M1,  M4)  which  project  beyond  the  tube 
and  can  be  moved  apart  along  the  supporting  arm. 
These  take  the  place  of  the  two  holes  over  the  object- 
glass  in  our  experiment.  From  these  mirrors  the 
light  is  reflected  to  a  second  pair  of  flat  mirrors 
(M2,  M3),  which  send  it  toward  the  loo-inch  con- 
cave mirror  (M5)  at  the  bottom  of  the  telescope  tube. 
After  this  the  course  of  the  light  is  exactly  as  it 
would  be  if  the  mirrors  M2,  M3  were  replaced  by  two 
holes  over  the  loo-inch  mirror.  It  is  reflected  to 
the  convex  mirror  (M6),  then  back  in  a  less  rapidly 
convergent  beam  toward  the  large  mirror.  Before 
reaching  it  the  light  is  caught  by  the  plane  mirror 
(M7)  and  reflected  through  an  opening  at  the  side 
of  the  telescope  tube  to  the  eye-piece  E.  Here  the 
fringes  are  observed  with  a  magnification  ranging 
from  1,500  to  3,000  diameters. 

In  the  practical  application  of  this  method  to  the 
measurement  of  star  diameters,  the  chief  problem 
was  whether  the  atmosphere  would  be  quiet  enough 
to  permit  sharp  interference  fringes  to  be  produced 
with  light-pencils  more  than  100  inches  apart. 
After  successful  preliminary  tests  with  the  4O-inch 
refracting  telescope  of  the  Yerkes  Observatory,  Pro- 
fessor Michelson  made  the  first  attempt  to  see  the 
fringes  with  the  6o-inch  and  loo-inch  reflectors  on 
Mount  Wilson  in  September,  1919.  He  was  sur- 
prised and  delighted  to  find  that  the  fringes  were 
perfectly  sharp  and  distinct  with  the  full  aperture 
[46! 

/ 

it/-      < 


GIANT    STARS 

of  both  these  instruments.  Doctor  Anderson,  of 
the  observatory  staff,  then  devised  a  special  form 
of  interferometer  for  the  measurement  of  close 
double  stars,  and  applied  it  with  the  loo-inch  tele- 


Fig.   24.     Twenty-foot  Michelson  interferometer  for  measuring 

star  diameters,  attached  to  upper  end  of  the  skeleton 

tube  of  the  loo-inch  Hooker  telescope. 

The  path  of  the  two  pencils  of  light  from  the  star  is  shown  in  Fig.  23.    For 
a  photograph  of  the  entire  telescope,  see  Fig.  4. 


scope  to  the  measurement  of  the  orbital  motion  of 
the  close  components  of  Capella,  with  results  of 
extraordinary  accuracy,  far  beyond  anything  at- 
tainable by  previous  methods.  The  success  of  this 
work  strongly  encouraged  the  more  ambitious  proj- 
ect of  measuring  the  diameter  of  a  star,  and  the 
20-foot  interferometer  was  built  for  this  purpose. 


THE    NEW    HEAVENS 

The  difficult  and  delicate  problem  of  adjusting  the 
mirrors  of  this  instrument  with  the  necessary  ex- 
treme accuracy  was  solved  by  Professor  Michelson 
during  his  visit  to  Mount  Wilson  in  the  summer  of 
1920,  and  with  the  assistance  of  Mr.  Pease,  of  the 
observatory  staff,  interference  fringes  were  observed 
in  the  case  of  certain  stars  when  the  mirrors  were  as 
much  as  1 8  feet  apart.  All  was  thus  in  readiness 
for  a  decisive  test  as  soon  as  a  suitable  star  presented 
itself. 

THE    GIANT    BETELGEUSE 

Russell,  Shapley,  and  Eddingtor,  had  pointed  out 
Betelgeuse  (Arabic  for  "the  giant's  shoulder"),  the 
bright  red  star  in  the  constellation  of  Orion  (Fig. 
25),  as  the  most  favorable  of  all  stars  for  measure- 
ment, and  the  last-named  had  given  its  angular 
diameter  as  0.051  of  a  second  of  arc.  This  deduction 
from  theory  appeared  in  his  recent  presidential  ad- 
dress before  the  British  Association  for  the  Advance- 
ment of  Science,  in  which  Professor  Eddington  re- 
marked: "Probably  the  greatest  need  of  stellar 
astronomy  at  the  present  day,  in  order  to  make  sure 
that  our  theoretical  deductions  are  starting  on  the 
right  lines,  is  some  means  of  measuring  the  apparent 
angular  diameter  of  stars."  He  then  referred  to  the 
work  already  in  progress  on  Mount  Wilson,  but 
anticipated  "that  atmospheric  disturbance  will  ulti- 
mately set  the  limit  to  what  can  be  accomplished." 

On  December  13,  1920,  Mr.  Pease  successfully 
measured  the  diameter  of  Betelgeuse  with  the  20- 

[48] 


Fig.  25.     The  giant  Betelgeuse  (within  the  circle),  familiar  as  the 
conspicuous  red  star  in  the  right  shoulder  of  Orion  (Hubble). 

Measures  with  the  interferometer  show  its  angular'diameter  to  be  0.047  of  a  sec- 
ond of  arc,  corresponding  to  a  linear  diameter  of  215,000,000  miles,  if  the 
best  available  determination  of  its  distance  can  be  relied  upon.  This  de- 
termination shows  Betelgeuse  to  be  160  light-years  from  the  earth.  Light 
travels  at  the  rate  of  186,000  miles  per  second,  and  yet  spends  160  years  on 
its  journey  to  us  from  this  star. 


THE    NEW    HEAVENS 

foot  interferometer.  As  the  outer  mirrors  were 
separated  the  interference  fringes  gradually  became 
less  distinct,  as  theory  requires,  and  as  Doctor 
Merrill  had  previously  seen  when  observing  Betel- 
geuse  with  the  interferometer  used  for  Capella.  At 
a  separation  of  10  feet  the  fringes  disappeared  com- 
pletely, giving  the  data  required  for  calculating  the 
diameter  of  the  star.  To  test  the  perfection  of  the 
adjustment,  the  telescope  was  turned  to  other  stars, 
of  smaller  angular  diameter,  which  showed  the 
fringes  with  perfect  clearness.  Turning  back  to 
Betelgeuse,  they  were  seen  beyond  doubt  to  be  ab- 
sent. Assuming  the  mean  wave-length  of  the  light 
of  this  star  to  be  j^rfrJffiR  of  a  millimetre,  its  angular 
diameter  comes  out  0.047  of  a  second  of  arc,  thus 
falling  between  the  values — 0.051  and  0.031  of  a 
second — predicted  by  Eddington  and  Russell  from 
slightly  different  assumptions.  Subsequent  correc- 
tions and  repeated  measurement  will  change  Mr. 
Pease's  result  somewhat,  but  it  is  almost  certainly 
within  10  or  15  per  cent  of  the  truth.  We  may  there- 
fore conclude  that  the  angular  diameter  of  Betel- 
geuse is  very  nearly  the  same  as  that  of  a  ball 
one  inch  in  diameter,  seen  at  a  distance  of  seventy 
miles. 

But  this  represents  only  the  angle  subtended  by 
the  star's  disk.  To  learn  its  linear  diameter,  we 
must  know  its  distance.  Four  determinations  of  the 
parallax,  which  determines  the  distance,  have  been 
made.  Elkin,  with  the  Yale  heliometer,  obtained 
0.032  of  a  second  of  arc.  Schlesinger,  from  photo- 
[  50  ] 


GIANT    STARS 

graphs  taken  with  the  3O-inch  Allegheny  refractor, 
derived  0.016.    Adams,  by  his  spectroscopic  method 


Fig.  26.     Arcturus  (within  the  white  circle),  known  to  the  Arabs 

as  the  "Lance  Bearer,"  and  to  the  Chinese  as  the  "Great 

Horn"  or  the  "Palace  of  the  Emperors"  (Hubble). 

Its  angular  diameter,  measured  at  Mount  Wilson  by  Pease  with  the  2O-foot 
Michelson  interferometer  on  April  15,  1921,  is  0.022  of  a  second,  in  close 
agreement  with  Russell's  predicted  value  of  0.019  of  a  second.  The  mean 
parallax  of  Arcturus,  based  upon  several  determinations,  is  0.095  °f  a  second, 
corresponding  to  a  distance  of  34  light-years.  The  linear  diameter,  com- 
puted from  Pease's  measure  and  this  value  of  the  distance  is  about  21  mil- 
lion miles. 

applied  with  the   6o-inch    Mount  Wilson  reflector, 
obtained   0.012.    Lee's  recent  value,  secured  photo- 

tsi  i 


THE    NEW    HEAVENS 

graphically  with  the4O-inch  Yerkes  refractor,  is  0.022. 
The  heliometer  parallax  is  doubtless  less  reliable 
than  the  photographic  ones,  and  Doctor  Adams 
states  that  the  spectral  type  and  luminosity  of  Betel- 
geuse  make  his  value  less  certain  than  in  the  case 
of  most  other  stars.  If  we  take  a  (weighted)  mean 
value  of  0.020  of  a  second,  we  shall  probably  not  be 
far  from  the  truth.  This  parallax  represents  the 
angle  subtended  by  the  radius  of  the  earth's  orbit 
(93,000,000  miles)  at  the  distance  of  Betelgeuse. 
By  comparing  it  with  0.047,  the  angular  diameter 
of  the  star,  we  see  that  the  linear  diameter  is  about 
two  and  one-third  times  as  great  as  the  distance 
from  the  earth  to  the  sun,  or  approximately  215,- 
000,000  miles.  Thus,  if  this  measure  of  its  distance 
is  not  considerably  in  error,  Betelgeuse  would  nearly 
fill  the  orbit  of  Mars.  All  methods  of  determining 
the  distances  of  the  stars  are  subject  to  uncertainty, 
however,  and  subsequent  measures  may  reduce  this 
figure  very  appreciably.  But  there  can  be  no  doubt 
that  the  diameter  of  Betelgeuse  exceeds  100,000,000 
miles,  and  it  is  probably  much  greater. 

The  extremely  small  angle  subtended  by  this 
enormous  disk  is  explained  by  the  great  distance  of 
the  star,  which  is  about  160  light-years.  That  is  to 
say,  light  travelling  at  the  rate  of  186,000  miles  per 
second  spends  160  years  in  crossing  the  space  that 
lies  between  us  and  Betelgeuse,  whose  tremendous 
proportions  therefore  seem  so  minute  even  in  the 
most  powerful  telescopes. 

[    52    1 


GIANT    STARS 

STELLAR  EVOLUTION 

This  actual  measure  of  the  diameter  of  Betelgeuse 
supplies  a  new  and  striking  test  of  Russell's  and 
Hertzsprung's  theory  of  dwarf  and  giant  stars. 
Just  before  the  war  Russell  showed  that  our  old 
methods  of  classifying  the  stars  according  to  their 
spectra  must  be  radically  changed.  Stars  in  an 
early  stage  of  their  life  history  may  be  regarded  as 
diffuse  gaseous  masses,  enormously  larger  than  our 
sun,  and  at  a  much  lower  temperature.  Their 
density  must  be  very  low,  and  their  state  that  of  a 
perfect  gas.  These  are  the  "giants."  In  the  slow 
process  of  time  they  contract  through  constant 
loss  of  heat  by  radiation.  But,  despite  this  loss, 
the  heat  produced  by  contraction  and  from  other 
sources  (see  p.  82)  causes  their  temperature  to  rise, 
while  their  color  changes  from  red  to  bluish  white. 
The  process  of  shrinkage  and  rise  of  temperature 
goes  on  so  long  as  they  remain  in  the  state  of  a  per- 
fect gas.  But  as  soon  as  contraction  has  increased 
the  density  of  the  gas  beyond  a  certain  point  the 
cycle  reverses  and  the  temperature  begins  to  fall. 
The  bluish-white  light  of  the  star  turns  yellowish, 
and  we  enter  the  dwarf  stage,  of  which  our  own  sun 
is  a  representative.  The  density  increases,  surpass- 
ing that  of  water  in  the  case  of  the  sun,  and  going 
far  beyond  this  point  in  later  stages.  In  the  lapse 
of  millions  of  years  a  reddish  hue  appears,  finally 
turning  to  deep  red.  The  falling  temperature  per- 

[53 1 


THE    NEW    HEAVENS 

mits  the  chemical  elements,  existing  in  a  gaseous 
state  in  the  outer  atmosphere  of  the  star,  to  unite 
into  compounds,  which  are  rendered  conspicuous  by 


Fig.  27.     The  giant  star  Antares  (within  the  white  circle),  notable 

for  its  red  color  in  the  constellation  Scorpio,  and  named 

by  the  Greeks  "A  Rival  of  Mars"  (Hubble). 

The  distance  of  Antares,  though  not  very  accurately  known,  is  probably  not  far 
from  350  light-years.  Its  angular  diameter  of  0.040  of  a  second  would  thus 
correspond  to  a  linear  diameter  of  about  400  million  miles. 

their  characteristic  bands  in  the  spectrum.  Finally 
comes  extinction  of  light,  as  the  star  approaches  its 
ultimate  state  of  a  cold  and  solid  globe. 

We  may  thus   form   a  new  picture  of  the  two 
branches  of  the  temperature  curve,  long  since  sug- 

1 54] 


GIANT    STARS 

gested  by  Lockyer,  on  very  different  grounds,  as  the 
outline  of  stellar  life.  On  the  ascending  side  are 
the  giants,  of  vast  dimensions  and  more  diffuse  than 
the  air  we  breathe.  There  are  good  reasons  for 
believing  that  the  mass  of  Betelgeuse  cannot  be 
more  than  ten  times  that  of  the  sun,  while  its  volume 
is  at  least  a  million  times  as  great  and  may  exceed 
eight  million  times  the  sun's  volume.  Therefore, 
its  average  density  must  be  like  that  of  an  atten- 
uated gas  in  an  electric  vacuum  tube.  Three- 
quarters  of  the  naked-eye  stars  are  in  the  giant 
stage,  which  comprises  such  familiar  objects  as 
Betelgeuse,  Antares,  and  Aldebaran,  but  most  of 
them  are  much  denser  than  these  greatly  inflated 
bodies.  The  pinnacle  is  reached  in  the  intensely  hot 
white  stars  of  the  helium  class,  in  whose  spectra  the 
lines  of  this  gas  are  very  conspicuous.  The  density 
of  these  stars  is  perhaps  one-tenth  that  of  the  sun. 
Sirius,  also  very  hot,  is  nearly  twice  as  dense.  Then 
comes  the  cooling  stage,  characterized,  as  already 
remarked,  by  increasing  density,  and  also  by  increas- 
ing chemical  complexity  resulting  from  falling  tem- 
perature. This  life  cycle  is  probably  not  followed 
by  all  stars,  but  it  may  hold  true  for  millions  of 
them. 

The  existence  of  giant  and  dwarf  stars  has  been 
fully  proved  by  the  remarkable  work  of  Adams  and 
his  associates  on  Mount  Wilson,  where  his  method 
of  determining  a  star's  distance  and  intrinsic  lumi- 
nosity by  spectroscopic  observations  has  already 
been  applied  to  2,000  stars.  Discussion  of  the  re- 
[  55  1 


THE    NEW    HEAVENS 

suits  leads  at  once  to  the  recognition  of  the  two 
great  classes  of  giants  and  dwarfs.  Now  comes  the 
work  of  Michelson  and  Pease  to  cap  the  climax,  giv- 
ing us  the  actual  diameter  of  a  typical  giant  star,  in 
close  agreement  with  predictions  based  upon  theory. 
From  this  diameter  we  may  conclude  that  the 
density  of  Betelgeuse  is  extremely  low,  in  harmony 
with  Russell's  theory,  which  is  further  supported 
by  spectroscopic  analysis  of  the  star's  light,  reveal- 
ing evidence  of  the  comparatively  low  temperature 
called  for  by  the  theory  at  this  early  stage  of  stellar 
existence. 

TWO    OTHER    GIANTS 

The  diameter  of  Arcturus  was  successfully  mea- 
sured by  Mr.  Pease  at  Mount  Wilson  on  April  15. 
As  the  mirrors  of  the  interferometer  were  moved 
apart,  the  fringes  gradually  decreased  in  visibility 
until  they  finally  disappeared  at  a  mirror  separation 
of  19.6  feet.  Adopting  a  mean  wave-length  of 
Ti)Mo1ro¥  of  a  millimetre  for  the  light  of  Arcturus, 
this  gives  a  value  of  0.022  of  a  second  of  arc  for  the 
angular  diameter  of  the  star.  If  we  use  a  mean 
value  of  0.095  °f  a  second  for  the  parallax,  the  corre- 
sponding linear  diameter  comes  out  21,000,000  miles. 
The  angular  diameter,  as  in  the  case  of  Betelgeuse, 
is  in  remarkably  close  agreement  with  the  diameter 
predicted  from  theory.  Antares,  the  third  star  mea- 
sured by  Mr.  Pease,  is  the  largest  of  all.  If  it  is 
actually  a  member  of  the  Scorpius-Centaurus  group, 
as  we  have  strong  reason  to  believe,  it  is  fully  350 
[  56] 


GIANT    STARS 

light-years  from  the  earth,  and  its  diameter  is  about 
400,000,000  miles. 


Fig.  28.    Diameters  of  the  Sun,  Arcturus,  Betelgeuse,  and  Antares 
compared  with  the  orbit  of  Mars. 
.     Sun,  diameter,  865,000  miles. 

j     Arcturus,  diameter,  21,000,000  miles. 

Betelgeuse,  diameter,  215,000,000  miles, 
liijjiji]     Antares,  diameter,  400,000,000  miles. 

It  now  remains  to  make  further  measures  of  Betel- 
geuse, especially  because  its  marked  changes  in 
brightness  suggest  possible  variations  in  diameter. 

[57] 


THE    NEW    HEAVENS 

We  must  also  apply  the  interferometer  method  to 
stars  of  the  various  spectral  types,  in  order  to  afford 
a  sure  basis  for  future  studies  of  stellar  evolution. 
Unfortunately,  only  a  few  giant  stars  are  certain  to 
fall  within  the  range  of  our  present  instrument.  An 
interferometer  of  yo-feet  aperture  would  be  needed 
to  measure  Sirius  accurately,  and  one  of  twice  this 
size  to  deal  with  less  brilliant  white  stars.  A  100- 
foot  instrument,  if  feasible  to  build,  would  permit 
objects  representing  most  of  the  chief  stages  of 
stellar  development  to  be  measured,  thus  contrib- 
uting in  the  highest  degree  to  the  progress  of  our 
knowledge  of  the  life  history  of  the  stars.  Fortu- 
nately, though  the  mechanical  difficulties  are  great, 
the  optical  problem  is  insignificant,  and  the  cost  of 
the  entire  apparatus,  though  necessarily  high,  would 
be  only  a  small  fraction  of  that  of  a  telescope  of  cor- 
responding aperture,  if  such  could  be  built.  A  100- 
foot  interferometer  might  be  designed  in  many  dif- 
ferent forms,  and  one  of  these  may  ultimately  be 
found  to  be  within  the  range  of  possibility.  Mean- 
while the  2O-foot  interferometer  has  been  improved 
so  materially  that  it  now  promises  to  yield  approx- 
imate measures  of  stars  at  first  supposed  to  be  be- 
yond its  capacity. 

While  the  theory  of  dwarf  and  giant  stars  and  the 
measurements  just  described  afford  no  direct  evi- 
dence bearing  on  Laplace's  explanation  of  the  forma- 
tion of  planets,  they  show  that  stars  exist  which  are 
comparable  in  diameter  with  our  solar  system,  and 
suggest  that  the  sun  must  have  shrunk  from  vast 
[  58  ] 


Fig.   29.     Aldebaran,  the  "leader"   (of  the  Pleiades),  was  also 

known  to  the  Arabs  as  "The  Eye  of  the  Bull,"  "The 

Heart  of  the  Bull,"  and  "The  Great  Camel" 

(Hubble). 

Like  Betelgeuse  and  Antares,  it  is  notable  for  its  red  color,  which  accounts  for 
the  fact  that  its  image  on  this  photograph  is  hardly  more  conspicuous  than 
the  images  of  stars  which  are  actually  much  fainter  but  contain  a  larger  pro- 
portion of  blue  light,  to  which  the  photographic  plates  here  employed  are 
more  sensitive  than  to  red  or  yellow.  Aldebaran  is  about  50  light-years 
from  the  earth.  Interferometer  measures,  now  in  progress  on  Mount 
Wilson,  indicate  that  its  angular  diameter  is  about  0.020  of  a  second. 


THE    NEW    HEAVENS 

dimensions.  The  mode  of  formation  of  systems 
like  our  own,  and  of  other  systems  numerously  illus- 
trated in  the  heavens,  is  one  of  the  most  fascinating 
problems  of  astronomy.  Much  light  has  been 
thrown  on  it  by  recent  investigations,  rendered  pos- 
sible by  the  development  of  new  and  powerful  in- 
struments and  by  advances  in  physics  of  the  most 
fundamental  character.  All  the  evidence  confirms 
the  existence  of  dwarf  and  giant  stars,  but  much 
work  must  be  done  before  the  entire  course  of 
stellar  evolution  can  be  explained. 


60 


CHAPTER  III 
COSMIC  CRUCIBLES 

"SHELTER  during  Raids,"  marking  the  entrance 
to  underground  passages,  was  a  sign  of  common  oc- 
currence and  sinister  suggestion  throughout  London 
during  the  war.  With  characteristic  ingenuity  and 
craftiness,  ostensibly  for  purposes  of  peace  but  with 
bomb-carrying  capacity  as  a  prime  specification,  the 
Zeppelin  had  been  developed  by  the  Germans  to  a 
point  where  it  seriously  threatened  both  London  and 
Paris.  Searchlights,  range-finders,  and  anti-aircraft 
guns,  surpassed  by  the  daring  ventures  of  British 
and  French  airmen,  would  have  served  but  little 
against  the  night  invader  except  for  its  one  fatal  de- 
fect— the  inflammable  nature  of  the  hydrogen  gas 
that  kept  it  aloft.  A  single  explosive  bullet  served 
to  transform  a  Zeppelin  into  a  heap  of  scorched 
and  twisted  metal.  This  characteristic  of  hydrogen 
caused  the  failure  of  the  Zeppelin  raids. 

Had  the  war  lasted  a  few  months  longer,  however, 
the  work  of  American  scientists  would  have  made 
our  counter-attack  in  the  air  a  formidable  one.  At 
the  signing  of  the  armistice  hundreds  of  cylinders  of 
compressed  helium  lay  at  the  docks  ready  for  ship- 
ment abroad.  Extracted  from  the  natural  gas  of 
Texas  wells  by  new  and  ingenious  processes,  this 

[6!    ] 


THE    NEW    HEAVENS 

substitute  for  hydrogen,  almost  as  light  and  abso- 
lutely uninflammable,  produced  in  quantities  of  mil- 
lions of  cubic  feet,  would  have  made  the  dirigibles 
of  the  Allies  masters  of  the  air.  The  special  proper- 
ties of  this  remarkable  gas,  previously  obtainable 
only  in  minute  quantities,  would  have  sufficed  to  re- 
verse the  situation. 

SOLAR   HELIUM 

Helium,  as  its  name  implies,  is  of  solar  origin.  In 
1868,  when  Lockyer  first  directed  his  spectroscope 
to  the  great  flames  or  prominences  that  rise  thou- 
sands of  miles,  sometimes  hundreds  of  thousands, 
above  the  surface  of  the  sun,  he  instantly  identified 
the  characteristic  red  and  blue  radiations  of  hydro- 
gen. In  the  yellow,  close  to  the  position  of  the  well- 
known  double  line  of  sodium,  but  not  quite  coinci- 
dent with  it,  he  detected  a  new  line,  of  great  bril- 
liancy, extending  to  the  highest  levels.  Its  similar- 
ity in  this  respect  with  the  lines  of  hydrogen  led  him 
to  recognize  the  existence  of  a  new  and  very  light 
gas,  unknown  to  terrestrial  chemistry. 

Many  years  passed  before  any  chemical  labora- 
tory on  earth  was  able  to  match  this  product  of  the 
great  laboratory  of  the  sun.  In  1896  Ramsay  at 
last  succeeded  in  separating  helium,  recognized  by 
the  same  yellow  line  in  its  spectrum,  in  minute 
quantities  from  the  mineral  uraninite.  Once  avail- 
able for  study  under  electrical  excitation  in  vacuum 
tubes,  helium  was  found  to  have  many  other  lines 
in  its  spectrum,  which  have  been  identified  in  the 
[  62  ] 


COSMIC    CRUCIBLES 

spectra  of  solar  prominences,  gaseous  nebulae,  and 
hot  stars.     Indeed,  there  is  a  stellar  class  known  as 


Fig.    30.     Solar   prominences,    photographed    with    the    spectro- 
heliograph  without  an  eclipse  (Ellerman). 

In  these  luminous  gaseous  clouds,  which  sometimes  rise  to  elevations  exceeding 
half  the  sun's  diameter,  the  new  gas  helium  was  discovered  by  Lockyer  in 
1868.  Helium  was  not  found  on  the  earth  until  1896.  Since  then  it  has 
been  shown  to  be  a  prominent  constituent  of  nebulae  and  hot  stars. 


helium  stars,  because  of  the  dominance  of  this  gas 
in  their  atmospheres. 

The  chief  importance  of  helium  lies  in  the  clue  it 
has  afforded  to  the  constitution  of  matter  and  the 
transmutation  of  the  elements.     Radium  and  other 
[  63  1 


THE    NEW    HEAVENS 

radioactive  substances,  such  as  uranium,  spontane- 
ously emit  negatively  charged  particles  of  extremely 
small  mass  (electrons),  and  also  positively  charged 
particles  of  much  greater  mass,  known  as  alpha  par- 
ticles. Rutherford  and  Geiger  actually  succeeded  in 
counting  the  number  of  alpha  particles  emitted  per 
second  by  a  known  mass  of  radium,  and  showed 
that  these  were  charged  helium  atoms. 

To  discuss  more  at  length  the  extraordinary  char- 
acteristics of  helium,  which  plays  so  large  a  part  in 
celestial  affairs,  would  take  us  too  far  afield.  Let 
us  therefore  pass  to  another  case  in  which  a  funda- 
mental discovery,  this  time  in  physics,  was  first 
foreshadowed  by  astronomical  observation. 

SUN-SPOTS    AS    MAGNETS 

No  archaeologist,  whether  Young  or  Champollion 
deciphering  the  Rosetta  Stone,  or  Rawlinson  copy- 
ing the  cuneiform  inscription  on  the  cliff  of  Behis- 
tun,  was  ever  faced  by  a  more  fascinating  problem 
than  that  which  confronts  the  solar  physicist  en- 
gaged in  the  interpretation  of  the  hieroglyphic  lines 
of  sun-spot  spectra.  The  colossal  whirling  storms 
that  constitute  sun-spots,  so  vast  that  the  earth 
would  make  but  a  moment's  scant  mouthful  for 
them,  differ  materially  from  the  general  light  of  the 
sun  when  examined  with  the  spectroscope.  Observ- 
ing them  visually  many  years  ago,  the  late  Professor 
Young,  of  Princeton,  found  among  their  complex 
features  a  number  of  double  lines  which  he  naturally 
attributed,  in  harmony  with  the  physical  knowledge 
[64] 


COSMIC    CRUCIBLES 

of  the  time,  to  the  effect  of  "reversal"  by  super- 
posed layers  of  vapors  of  different  density  and  tern- 


Fig.  31.     The  150-foot  tower  telescope  of  the  Mount 
Wilson  Observatory. 

An  image  of  the  sun  about  1 6  inches  in  _diameter  is  formed  in  the  laboratory  at 
the  base  of  the  tower.  Below  this,  in  a  well  extending  80  feet  into  the  earth, 
is  the  powerful  spectroscope  with  which  the  magnetic  fields  in  sun-spots 
and  the  general  magnetic  field  of  the  sun  are  studied. 

perature.     What  he  actually  saw,  however,  as  was 

proved  at  the  Mount  Wilson  Observatory  in  1908, 

[65  ] 


THE    NEW    HEAVENS 

was  the  effect  of  a  powerful  magnetic  field  on  radia- 
tion, now  known  as  the  Zeeman  effect. 

Faraday  was  the  first  to  detect  the  influence  of 
magnetism  on  light.  Between  the  poles  of  a  large 
electromagnet,  powerful  for  those  days  (1845),  ne 
placed  a  block  of  very  dense  glass.  The  plane  of 
polarization  of  a  beam  of  light,  which  passed  un- 
affected through  the  glass  before  the  switch  was 
closed,  was  seen  to  rotate  when  the  magnetic  field 
was  produced  by  the  flow  of  the  current.  A  similar 
rotation  is  now  familiar  in  the  well-known  tests  of 
sugars — laevulose  and  dextrose — which  rotate  plane- 
polarized  light  to  left  and  right,  respectively. 

But  in  this  first  discovery  of  a  relationship  be- 
tween light  and  magnetism  Faraday  had  not  taken 
the  more  important  step  that  he  coveted — to  deter- 
mine whether  the  vibration  period  of  a  light-emit- 
ting particle  is  subject  to  change  in  a  magnetic  field. 
He  attempted  this  in  1862 — the  last  experiment  of 
his  life.  A  sodium  flame  was  placed  between  the 
poles  of  a  magnet,  and  the  yellow  lines  were  watched 
in  a  spectroscope  when  the  magnet  was  excited. 
No  change  could  be  detected,  and  none  was  found 
by  subsequent  investigators  until  Zeeman,  of  Leiden, 
with  more  powerful  instruments  made  his  famous 
discovery,  the  twenty-fifth  anniversary  of  which 
has  recently  been  celebrated. 

His  method  of  procedure  was  similar  to  Faraday's, 

but  his  magnet  and  spectroscope  were  much  more 

powerful,  and  a  theory  due  to  Lorentz,  predicting 

the  nature  of  the  change  to  be  expected,  was  avail- 

[66] 


COSMIC    CRUCIBLES 

able  as  a  check  on  his  results.  When  the  current 
was  applied  the  lines  were  seen  to  widen.  In  a  still 
more  powerful  magnetic  field  each  of  them  split  into 
two  components  (when  the  observation  was  made 


Fig.  32.     Pasadena  Laboratory  of  the  Mount  Wilson 
Observatory. 

Showing  the  large  magnet  (on  the  left)  and  the  spectroscopes  used  for  the  study 
of  the  effect  of  magnetism  on  radiation.  A  single  line  in  the  spectrum  is 
split  by  the  magnetic  field  into  from  three  to  twenty-one  components,  as 
illustrated  in  Fig.  34.  The  corresponding  lines  in  the  spectra  of  sun-spots 
are  split  up  in  precisely  the  same  way,  thus  indicating  the  presence  of  power- 
ful magnetic  fields  in  the  sun. 

along  the  lines  of  force),  and  the  light  of  the  compo- 
nents of  each  line  was  found  to  be  circularly  polar- 
ized in  opposite  directions.  Strictly  in  harmony 
with  Lorentz's  theory,  this  splitting  and  polariza- 
tion proved  the  presence  in  the  luminous  vapor  of 

[67] 


THE    NEW    HEAVENS 

exactly  such  negatively  charged  electrons  as  had 
been  indicated  there  previously  by  very  different 
experimental  methods. 

In  1908  great  cyclonic  storms,  or  vortices,  were 
discovered  at  the  Mount  Wilson  Observatory  cen- 
tring in  sun-spots.  Such  whirling  masses  of  hot 
vapors,  inferred  from  Sir  Joseph  Thomson's  results 
to  contain  electrically  charged  particles,  should  give 
rise  to  a  magnetic  field.  This  hypothesis  at  once 
suggested  that  the  double  lines  observed  by  Young 
might  really  represent  the  Zeeman  effect.  The  test 
was  made,  and  all  the  characteristic  phenomena  of 
radiation  in  a  magnetic  field  were  found. 

Thus  a  great  physical  experiment  is  constantly 
being  performed  for  us  in  the  sun.  Every  large  sun- 
spot  contains  a  magnetic  field  covering  many  thou- 
sands of  square  miles,  within  which  the  spectrum 
lines  of  iron,  manganese,  chromium,  titanium,  vana- 
dium, calcium,  and  other  metallic  vapors  are  so 
powerfully  affected  that  their  widening  and  split- 
ting can  be  seen  with  telescopes  and  spectroscopes 
of  moderate  size. 

THE    TOWER   TELESCOPE 

Both  of  these  illustrations  show  how  the  physicist 
and  chemist,  when  adequately  armed  for  astronom- 
ical attack,  can  take  advantage  in  their  studies  of 
the  stupendous  processes  visible  in  cosmic  crucibles, 
heated  to  high  temperatures  and  influenced,  as  in 
the  case  of  sun-spots,  by  intense  magnetic  fields. 
Certain  modern  instruments,  like  the  6o-foot  and 
[68] 


COSMIC    CRUCIBLES 

150-foot  tower  telescopes  on  Mount  Wilson,^  are 
especially  designed  for  observing  the  course  of  these 
experiments.  The  second  of  these  telescopes  pro- 
duces at  a  fixed  point  in  a  laboratory  an  image  of 


Fig.  33.     Sun-spot  vortex  in  the  upper  hydrogen  atmosphere. 
(Benioff). 

Photographed  with  the  spectroheliograph.  The  electric  vortex  that  causes  the 
magnetic  field  of  the  spot  lies  at  a  lower  level,  and  is  not  shown  by  such 
photographs. 

the  sun  about  16  inches  in  diameter,  thus  enlarging 
the  sun-spots  to  such  a  scale  that  the  magnetic 
phenomena  of  their  various  parts  can  be  separately 
studied.  This  analysis  is  accomplished  with  a  spec- 
troscope 80  feet  in  length,  mounted  in  a  subter- 
ranean chamber  beneath  the  tower.  The  varied  re- 
sults of  such  investigations  cannot  be  described  here. 
Only  one  of  them  may  be  mentioned — the  discovery 
[69] 


THE    NEW    HEAVENS 

that  the  entire  sun,  rotating  on  its  axis,  is  a  great 
magnet.  Hence  we  may  reasonably  infer  that  every 
star,  and  probably  every  planet,  is  also  a  magnet, 
as  the  earth  has  been  known  to  be  since  the  days  of 
Gilbert's  "De  Magnete."  Here  lies  one  of  the  best 
clues  for  the  physicist  who  seeks  the  cause  of  mag- 
netism, and  attempts  to  produce  it,  as  Barnett  has 
recently  succeeded  in  doing,  by  rapidly  whirling 
masses  of  metal  in  the  laboratory. 

Perhaps  a  word  of  caution  should  be  interpolated 
at  this  point.  Solar  magnetism  in  no  wise  accounts 
for  the  sun's  gravitational  power.  Indeed,  its  at- 
traction cannot  be  felt  by  the  most  delicate  instru- 
ments at  the  distance  of  the  earth,  and  would  still 
be  unknown  were  it  not  for  the  influence  of  magne- 
tism on  light. 

Auroras,  magnetic  storms,  and  such  electric  cur- 
rents as  those  that  recently  deranged  several  Atlan- 
tic cables  are  due,  not  to  the  magnetism  of  the  sun 
or  its  spots,  but  probably  to  streams  of  electrons, 
shot  out  from  highly  disturbed  areas  of  the  solar 
surface  surrounding  great  sun-spots,  traversing 
ninety-three  million  miles  of  the  ether  of  space, 
and  penetrating  deep  into  the  earth's  atmosphere. 
These  striking  phenomena  lead  us  into  another 
chapter  of  physics,  which  limitations  of  space  for- 
bid us  to  pursue. 

STELLAR  CHEMISTRY 

Let  us  turn  again  to  chemistry,  and  see  where 
experiments  performed  in  cosmic  laboratories  can 

[70] 


COSMIC    CRUCIBLES 

serve  as  a  guide  to  the  investigator.  A  spinning 
solar  tornado,  incomparably  greater  in  scale  than 
the  devastating  whirlwinds  that  so  often  cut  narrow 


Fig.  34.     Splitting  of  spectrum  lines  by  a  magnetic  field 
(Babcock). 

The  upper  and  lower  strips  show  lines  in  the  spectrum  of  chromium,  observed 
without  a  magnetic  field.  When  subjected  to  the  influence  of  magnetism, 
these  single  lines  are  split  into  several  components.  Thus  the  first  line  on 
the  right  is  resolved  by  the  field  into  three  components,  one  of  which  (plane 
polarized)  appears  in  the  second  strip,  while  the  other  two,  which  are  po- 
larized in  a  plane  at  right  angles  to  that  of  the  middle  component,  are  shown 
on  the  third  strip.  The  next  line  is  split  by  the  magnetic  field  into  twelve 
components,  four  of  which  appear  in  the  second  strip  and  eight  in  the  third. 
The  magnetic  fields  in  sun-spots  affect  these  lines  in  precisely  the  same  way. 


paths  of  destruction  through  town  and  country  in 
the  Middle  West,  gradually  gives  rise  to  a  sun-spot. 
The  expansion  produced  by  the  centrifugal  force  at 
the  centre  of  the  storm  cools  the  intensely  hot  gases 

[71  1 


UNIVERSITY  OF  CALIFORNIA 

DEPARTMENT  OF  CIVIL   ENGINEERING 

BERKELEY.  CALIFORNIA 


THE    NEW    HEAVENS 

of  the  solar  atmosphere  to  a  point  where  chemical 
union  can  occur.  Titanium  and  oxygen,  too  hot  to 
combine  in  most  regions  of  the  sun,  join  to  form  the 
vapor  of  titanium  oxide,  characterized  in  the  sun- 
spot  spectrum  by  fluted  bands,  made  up  of  hundreds 
of  regularly  spaced  lines.  Similarly  magnesium  and 
hydrogen  combine  as  magnesium  hydride  and  cal- 
cium and  hydrogen  form  calcium  hydride.  None  of 
these  compounds,  stable  at  the  high  temperatures  of 
sun-spots,  has  been  much  studied  in  the  laboratory. 
The  regions  in  which  they  exist,  though  cooler  than 
the  general  atmosphere  of  the  sun,  are  at  tempera- 
tures of  several  thousand  degrees,  attained  in  our 
laboratories  only  with  the  aid  of  such  devices  as 
powerful  electric  furnaces. 

It  is  interesting  to  follow  our  line  of  reasoning  to 
the  stars,  which  differ  widely  in  temperature  at 
various  stages  in  their  life-cycle.*  A  sun-spot  is  a 
solar  tornado,  wherein  the  intensely  hot  solar  vapors 
are  cooled  by  expansion,  giving  rise  to  the  com- 
pounds already  named.  A  red  star,  in  Russell's 
scheme  of  stellar  evolution,  is  a  cooler  sun,  vast  in 
volume  and  far  more  tenuous  than  atmospheric  air 
when  in  the  initial  period  of  the  "giant"  stage,  but 
compressed  and  denser  than  water  in  the  "dwarf" 
stage,  into  which  our  sun  has  already  entered  as  it 
gradually  approaches  the  last  phases  of  its  existence. 
Therefore  we  should  find,  throughout  the  entire 
atmosphere  of  such  stars,  some  of  the  same  com- 
pounds that  are  produced  within  the  comparatively 
*  See  Chapter  II. 
[72] 


COSMIC    CRUCIBLES 

small  limits  of  a  sun-spot.  This,  of  course,  on  the 
correct  assumption  that  sun  and  stars  are  made  of 
the  same  substances.  Fowler  has  already  identified 
the  bands  of  titanium  oxide  in  such  red  stars  as  the 
giant  Betelgeuse,  and  in  others  of  its  class.  It  is 


Fig.    35.     Electric  furnace   in   the  Pasadena  laboratory  of  the 
Mount  Wilson  Observatory. 

With  which  the  chemical  phenomena  observed  in  sun-spots  and  red 
stars  are  experimentally  imitated. 


safe  to  predict  that  an  interesting  chapter  in  the 
chemistry  of  the  future  will  be  based  upon  the  study 
of  such  compounds,  both  in  the  laboratory  and  under 
the  progressive  temperature  conditions  afforded  by 
the  countless  stellar  "giants"  and  "dwarfs"  that 
precede  and  follow  the  solar  state. 

[73 1 


THE  NEW  HEAVENS 

ASTROPHYSICAL  LABORATORIES 

It  is  precisely  in  this  long  sequence  of  physical 
and  chemical  changes  that  the  astrophysicist  and 
the  astrochemist  can  find  the  means  of  pushing  home 
their  attack.  It  is  true,  of  course,  that  the  labora- 
tory investigator  has  a  great  advantage  in  his  ability 
to  control  his  experiments,  and  to  vary  their  progress 
at  will.  But  by  judicious  use  of  the  transcendental 
temperatures,  far  outranging  those  of  his  furnaces, 
and  extreme  conditions,  which  he  can  only  partially 
imitate,  afforded  by  the  sun,  stars,  and  nebulae,  he 
may  greatly  widen  the  range  of  his  inquiries.  The 
sequence  of  phenomena  seen  during  the  growth  of 
a  sun-spot,  or  the  observation  of  spots  of  different 
sizes,  and  the  long  series  of  successive  steps  that 
mark  the  rise  and  decay  of  stellar  life,  resemble 
the  changes  that  the  experimenter  brings  about  as 
he  increases  and  diminishes  the  current  in  the  coils 
of  his  magnet  or  raises  and  lowers  the  temperature 
of  his  electric  furnace,  examining  from  time  to  time 
the  spectrum  of  the  glowing  vapors,  and  noting  the 
changes  shown  by  the  varving  appearance  of  their 
lines. 

Astronomical  observations  of  this  character,  it 
should  be  noted,  are  most  effective  when  constantly 
tested  and  interpreted  by  laboratory  experiment. 
Indeed,  a  modern  astrophysical  observatory  should 
be  equipped  like  a  great  physical  laboratory,  pro- 
vided on  the  one  hand  with  telescopes  and  accessory 
apparatus  of  the  greatest  attainable  power,  and  on 

[74] 


THE    NEW    HEAVENS 

the  other  with  every  device  known  to  the  investi- 
gator of  radiation  and  the  related  physical  and 
chemical  phenomena.  Its  telescopes,  especially  de- 
signed with  the  aims  of  the  physicist  and  chemist 
in  view,  bring  images  of  sun,  stars,  nebulae,  and  other 
heavenly  bodies  within  the  reach  of  powerful  spec- 
troscopes, sensitive  bolometers  and  thermopiles,  and 
the  long  array  of  other  appliances  available  for  the 
measurement  and  analysis  of  radiation.  Its  elec- 
tric furnaces,  arcs,  sparks,  and  vacuum  tubes,  its 
apparatus  for  increasing  and  decreasing  pressure, 
varying  chemical  conditions,  and  subjecting  lumi- 
nous gases  and  vapors  to  the  influence  of  electric 
and  magnetic  fields,  provide  the  means  of  imitating 
celestial  phenomena,  and  of  repeating  and  interpret- 
ing the  experiments  observed  at  the  telescope.  And 
the  advantage  thus  derived,  as  we  have  seen,  is 
not  confined  to  the  astronomer,  who  has  often  been 
able,  by  making  fundamental  physical  and  chemical 
discoveries,  to  repay  his  debt  to  the  physicist  and 
chemist  for  the  apparatus  and  methods  which  he 
owes  to  them. 

NEWTON  AND   EINSTEIN 

Take,  for  another  example,  the  greatest  law  of 
physics — Newton's  law  of  gravitation.  Huge  balls 
of  lead,  as  used  by  Cavendish,  produce  by  their 
gravitational  effect  a  minute  rotation  of  a  delicately 
suspended  bar,  carrying  smaller  balls  at  its  extremi- 
ties. But  no  such  feeble  means  sufficed  for  New- 
ton's purpose.  To  prove  the  law  of  gravitation  he 
[76] 


COSMIC    CRUCIBLES 

had  recourse  to  the  tremendous  pull  on  the  moon  of 
the  entire  mass  of  the  earth,  and  then  extended  his 
researches  to  the  mutual  attractions  of  all  the  bodies 
of  the  solar  system.  Later  Herschel  applied  this 


Fig.  38.     The  Cavendish  experiment. 

Two  lead  balls,  each  two  inches  in  diameter,  are  attached  to  the  ends  of  a  torsion 
rod  six  feet  long,  which  is  suspended  by  a  fine  wire.  The  experiment  consists 
in  measuring  the  rotation  of  the  suspended  system,  caused  by  the  gravita- 
tional attraction  of  two  lead  spheres,  each  twelve  inches  in  diameter,  acting 
on  the  two  small  lead  balls. 


law  to  the  suns  which  constitute  double  stars,  and 
to-day  Adams  observes  from  Mount  Wilson  stars 
falling  with  great  velocity  toward  the  centre  of  the 
galactic  system  under  the  combined  pull  of  the  mil- 
lions of  objects  that  compose  it.  Thus  full  advan- 
tage has  been  taken  of  the  possibility  of  utilizing 
the  great  masses  of  the  heavenly  bodies  for  the  dis- 
[77] 


THE    NEW    HEAVENS 

covery  and  application  of  a  law  of  physics  and  its 
reciprocal  use  in  explaining  celestial  motions. 

Or  consider  the  Einstein  theory  of  relativity,  the 
truth  or  falsity  of  which  is  no  less  fundamental  to 
physics.  Its  inception  sprang  from  the  Michelson- 
Morley  experiment,  made  in  a  laboratory  in  Cleve- 
land, which  showed  that  motion  of  the  earth  through 
the  ether  of  space  could  not  be  detected.  All  of  the 
three  chief  tests  of  Einstein's  general  theory  are 
astronomical — because  of  the  great  masses  required 
to  produce  the  minute  effects  predicted:  the  motion 
of  the  perihelion  of  Mercury,  the  deflection  of  the 
light  of  a  star  by  the  attraction  of  the  sun,  and  the 
shift  of  the  lines  of  the  solar  spectrum  toward  the 
red — questions  not  yet  completely  answered. 

But  it  is  in  the  study  of  the  constitution  of  matter 
and  the  evolution  of  the  elements,  the  deepest  and 
most  critical  problem  of  physics  and  chemistry, 
that  the  extremes  of  pressure  and  temperature  in 
the  heavenly  bodies,  and  the  prevalence  of  other 
physical  conditions  not  yet  successfully  imitated  on 
earth,  promise  the  greatest  progress.  It  fortunately 
happens  that  astrophysical  research  is  now  at  the 
very  apex  of  its  development,  founded  as  it  is  upon 
many  centuries  of  astronomical  investigation,  rejuve- 
nated by  the  introduction  into  the  observatory  of  all 
the  modern  devices  of  the  physicist,  and  strength- 
ened with  instruments  of  truly  extraordinary  range 
and  power.  These  instruments  bring  within  reach 
experiments  that  are  in  progress  on  some  minute 

[78] 


COSMIC    CRUCIBLES 

region  of  the  sun's  disk,  or  in  some  star  too  distant 
even  to  be  glimpsed  with  ordinary  telescopes.  In- 
deed, the  huge  astronomical  lenses  and  mirrors  now 
available  serve  for  these  remote  light-sources  exactly 
the  purpose  of  the  lens  or  mirror  employed  by  the 
physicist  to  project  upon  the  slit  of  his  spectroscope 
the  image  of  a  spark  or  arc  or  vacuum  tube  within 
which  atoms  and  molecules  are  exposed  to  the 
influence  of  the  electric  discharge.  The  physicist 
has  the  advantage  of  complete  control  over  the  ex- 
perimental conditions,  while  the  astrophysicist  must 
observe  and  interpret  the  experiments  performed  for 
him  in  remote  laboratories.  In  actual  practice,  the 
two  classes  of  work  must  be  done  in  the  closest  con- 
junction, if  adequate  utilization  is  to  be  made  of 
either.  And  this  is  only  natural,  for  the  trend  of 
recent  research  has  made  clear  the  fact  that  one  of 
the  three  greatest  problems  of  modern  astronomy 
and  astrophysics,  ranking  with  the  structure  of  the 
universe  and  the  evolution  of  celestial  bodies,  is 
the  constitution  of  matter.  Let  us  see  why  this  is  so. 

TRANSMUTATION  OF  THE  ELEMENTS 

The  dream  of  the  alchemist  was  to  transmute  one 
element  into  another,  with  the  prime  object  of  pro- 
ducing gold.  Such  transmutation  has  been  actually 
accomplished  within  the  last  few  years,  but  the 
process  is  invariably  one  of  disintegration — the  more 
complex  elements  being  broken  up  into  simpler  con- 
stituents. Much  remains  to  be  done  in  this  same 
direction;  and  here  the  stars  and  nebulae,  which 
[  791 


THE    NEW    HEAVENS 

show  the  spectra  of  the  elements  under  a  great 
variety  of  conditions,  should  help  to  point  the  way. 
The  progressive  changes  in  spectra,  from  the  ex- 
clusive indications  of  the  simple  element*  hydrogen, 
helium,  nitrogen,  possibly  carbon,  and  the  terrestri- 
ally unknown  gas  nebulium  in  the  gaseous  nebulae, 
to  the  long  list  of  familiar  substances,  including 
several  chemical  compounds,  in  the  red  stars,  may 
prove  to  be  fundamentally  significant  when  ade- 
quately studied  from  the  standpoint  of  the  investi- 
gator of  atomic  structure.  The  existing  evidence 
seems  to  favor  the  view,  recently  expressed  by  Saha, 
that  many  of  these  differences  are  due  to  varying 
degrees  of  ionization,  the  outer  electrons  of  the  atoms 
being  split  off  by  high  temperature  or  electrical 
excitation.  It  is  even  possible  that  cosmic  cruci- 
bles, unrivalled  by  terrestrial  ones,  may  help  ma- 
terially to  reveal  the  secret  of  the  formation  of 
complex  elements  from  simpler  ones.  Physicists 
now  believe  that  all  of  the  elements  are  compounded 
of  hydrogen  atoms,  bound  together  by  negative  elec- 
trons. Thus  helium  is  made  up  of  four  hydrogen 
atoms,  yet  the  atomic  weight  of  helium  (4)  is  less 
than  four  times  that  of  hydrogen  (1.008).  The 
difference  may  represent  the  mass  of  the  electrical 
energy  released  when  the  transmutation  occurred. 
Eddington  has  speculated  in  a  most  interesting 
way  on  this  possible  source  of  stellar  heat  in  his 
recent  presidential  address  before  the  British  Asso- 
ciation for  the  Advancement  of  Science  (see  Nature, 
September  2,  1920).  He  points  out  that  the  old 

[so] 


Fig.  39.     The  Trifid  Nebula  in  Sagittarius  (Ritchey). 

The  gas  "nebulium,"  not  yet  found  on  the  earth,  is  the  most  characteristic  con- 
stituent of  irregular  nebulae.  Nebulium  is  recognized  by  two  green  lines 
in  its  spectrum,  which  cause  the  green  color  of  nebulae  of  the  gaseous  type. 


THE    NEW    HEAVENS 

contraction  hypothesis,  according  to  which  the 
source  of  solar  and  stellar  heat  was  supposed  to  re- 
side in  the  slow  condensation  of  a  radiating  mass  of 
gas  under  the  action  of  gravity,  is  wholly  inadequate 
to  explain  the  observed  phenomena.  If  the  old 
view  were  correct,  the  earlier  history  of  a  star,  from 
the  giant  stage  of  a  cool  and  diaphanous  gas  to 
the  period  of  highest  temperature,  would  be  run 
through  within  eighty  thousand  years,  whereas  we 
have  the  best  of  evidence  that  many  thousands  of 
centuries  would  not  suffice.  Some  other  source  of 
energy  is  imperatively  needed.  If  5  per  cent  of  a 
star's  mass  consists  originally  of  hydrogen  atoms, 
which  gradually  combine  in  the  slow  process  of 
time  to  form  more  complex  elements,  the  total  heat 
thus  liberated  would  more  than  suffice  to  account 
for  all  demands,  and  it  would  be  unnecessary  to 
assume  the  existence  of  any  other  source  of  heat. 

COSMIC  PRESSURES 

This,  it  may  fairly  be  said,  is  very  speculative, 
but  the  fact  remains  that  celestial  bodies  appear  to 
be  the  only  places  in  which  the  complex  elements 
may  be  in  actual  process  of  formation  from  their 
known  source — hydrogen.  At  least  we  may  see 
what  a  vast  variety  of  physical  conditions  these 
cosmic  crucibles  afford.  At  one  end  of  the  scale  we 
have  the  excessively  tenuous  nebulae,  the  luminosity 
of  which,  mysterious  in  its  origin,  resembles  the 
electric  glow  in  our  vacuum  tubes.  Here  we  can 
detect  only  the  lightest  and  simplest  of  the  ele- 
[  82  ] 


Fig.  40.    Spiral  nebula  in  Ursa  Major  (Ritchey). 

Luminous  matter,  in  every  variety  of  physical  and  chemical  state,  is  available 
for  study  in  the  most  diverse  celestial  objects,  from  the  spiral  and  irregular 
nebulae  through  all  the  types  of  stars.  Doctor  van  Maanen's  measures  of 
the  Mount  Wilson  photographs  indicate  outward  motion  along  the  arms  of 
spiral  nebulae,  while  the  spectroscope  shows  them  to  be  whirling  at  enor- 
mous velocities. 


THE    NEW    HEAVENS 

ments.  In  the  giant  stars,  also  extremely  tenuous 
(the  density  of  Betelgeuse  can  hardly  exceed  one- 
thousandth  of  an  atmosphere)  we  observe  the  spec- 
tra of  iron,  manganese,  titanium,  calcium,  chromium, 
magnesium,  vanadium,  and  sodium,  in  addition  to 
titanium  oxide.  The  outer  part  of  these  bodies, 
from  which  light  reaches  us,  must  therefore  be  at  a 
temperature  of  only  a  few  thousand  degrees,  but 
vastly  higher  temperatures  must  prevail  at  their 
centres.  In  passing  up  the  temperature  curve  more 
and  more  elements  appear,  the  surface  temperature 
rises,  and  the  internal  temperature  may  reach  mil- 
lions of  degrees.  At  the  same  time  the  pressure 
within  must  also  rise,  reaching  enormous  figures  in 
the  last  stages  of  stellar  life.  Cook  has  calculated 
that  the  pressure  at  the  centre  of  the  earth  is  be- 
tween 4,000  and  10,000  tons  per  square  inch,  and 
this  must  be  only  a  very  small  fraction  of  that  at- 
tained within  larger  celestial  bodies.  Jeans  has 
computed  the  pressure  at  the  centre  of  two  colliding 
stars  as  they  strike  and  flatten,  and  finds  it  may  be 
of  the  order  of  1,000,000,000  tons  per  square  inch- 
sufficient,  if  their  diameter  be  equal  to  that  of  the 
sun — to  vaporize  them  100,000  times  over. 

Compare  these  pressures  with  the  highest  that 
can  be  produced  on  earth.  If  the  German  gun  that 
bombarded  Paris  were  loaded  with  a  solid  steel  pro- 
jectile of  suitable  dimensions,  a  muzzle  velocity  of 
6,000  feet  per  second  could  be  reached.  Suppose 
this  to  be  fired  into  a  tapered  hole  in  a  great  block  of 
steel.  The  instantaneous  pressure,  according  to 
[  84] 


COSMIC    CRUCIBLES 

Cook,  would  be  about  7,000  tons  per  square  inch, 
only  TTroinr  of  that  possible  through  the  collision  of 
the  largest  stars. 

Finally,  we  may  compare  the  effects  of  light  pres- 


Fig.  41.     Mount  San  Antonio  as  seen  from  Mount  Wilson. 

Michelson  is  measuring  the  velocity  of  light  between  stations  on  Mount  Wilson 
and  Mount  San  Antonio.  Astronomical  observations  afford  the  best  means, 
however,  of  detecting  any  possible  difference  between  the  velocities  of  light 
of  different  colors.  From  studies  of  variable  stars  in  the  cluster  Messier  5 
Shapley  concludes  that  if  there  is  any  difference  between  the  velocities  of 
blue  and  yellow  light  in  free  space  it  cannot  exceed  two  inches  in  one  second, 
the  time  in  which  light  travels  186,000  miles. 


sure  on  the  earth  and  stars.  Twenty  years  ago 
Nichols  and  Hull  succeeded,  with  the  aid  of  the 
most  sensitive  apparatus,  in  measuring  the  minute 
displacements  produced  by  the  pressure  of  light. 
The  effect  is  so  slight,  even  with  the  brightest  light- 
[  85  ] 


THE    NEW    HEAVENS 

sources  available,  that  great  experimental  skill  is 
required  to  measure  it.  Yet  in  the  case  of  some  of 
the  larger  stars  Eddington  calculates  that  one-half 
of  their  mass  is  supported  by  radiation  pressure, 
and  this  against  their  enormous  gravitational  at- 
traction. In  fact,  if  their  mass  were  as  great  as  ten 
times  that  of  the  sun,  the  radiation  pressure  would 
so  nearly  overcome  the  pull  of  gravitation  that  they 
would  be  likely  to  break  up. 

But  enough  has  Jbeen  said  to  illustrate  the  wide 
variety  of  experimental  devices  that  stand  at  our 
service  in  the  laboratories  of  the  heavens.  Here  the 
physicist  and  chemist  of  the  future  will  more  and 
more  frequently  supplement  their  terrestrial  ap- 
paratus, and  find  new  clues  to  the  complex  problems 
which  the  amazing  progress  of  recent  years  has  al- 
ready done  so  much  to  solve. 

PRACTICAL    VALUE    OF    RESEARCHES    ON    THE    CONSTI- 
TUTION OF  MATTER 

The  layman  has  no  difficulty  in  recognizing  the 
practical  value  of  researches  directed  toward  the 
improvement  of  the  incandescent  lamp  or  the  in- 
creased efficiency  of  the  telephone.  He  can  see  the 
results  in  the  greatly  decreased  cost  of  electric 
illumination  and  the  rapid  extension  of  the  range  of 
the  human  voice.  But  the  very  men  who  have 
made  these  advances,  those  who  have  succeeded  be- 
yond all  expectation  in  accomplishing  the  economic 
purposes  in  view,  are  most  emphatic  in  their  insis- 
[  86] 


COSMIC    CRUCIBLES 

tence  upon  the  importance  of  research  of  a  more 
fundamental  character.  Thus  Vice-President  J.  J. 
Carty,  of  the  American  Telephone  and  Telegraph 
Company,  who  directs  its  great  Department  of 
Development  and  Research,  and  Doctor  W.  J. 
Whitney,  Director  of  the  Research  Laboratory  of 
the  General  Electric  Company,  have  repeatedly 
expressed  their  indebtedness  to  the  investigations  of 
the  physicist,  made  with  no  thought  of  immediate 
practical  return.  Faraday,  studying  the  laws  of 
electricity,  discovered  the  principle  which  rendered 
the  dynamo  possible.  Maxwell,  Henry,  and  Hertz, 
equally  unconcerned  with  material  advantage,  made 
wireless  telegraphy  practicable.  In  fact,  all  truly 
great  advances  are  thus  derived  from  fundamental 
science,  and  the  future  progress  of  the  world  will 
be  largely  dependent  upon  the  provision  made  for 
scientific  research,  especially  in  the  fields  of  physics 
and  chemistry,  which  underlie  all  branches  of  engi- 
neering. 

The  constitution  of  matter,  therefore,  instead  of 
appealing  as  a  subject  to  research  only  to  the  natural 
philosopher  or  to  the  general  student  of  science,  is 
a  question  of  the  greatest  practical  concern.  Al- 
ready the  by-products  of  investigations  directed 
toward  its  elucidation  have  been  numerous  and 
useful  in  the  highest  degree.  Helium  has  been 
already  cited;  X-rays  hardly  require  mention;  ra- 
dium, which  has  so  materially  aided  sufferers  from 
cancer,  is  still  better  known.  Wireless  telephony 
and  transcontinental  telephony  with  wires  were  both 
[87] 


THE    NEW    HEAVENS 

rendered  possible  by  studies  of  the  nature  of  the 
electric  discharge  in  vacuum  tubes.  Thus  the 
"practical  man,"  with  his  distrust  of  "pure"  sci- 
ence, need  not  resent  investments  made  for  the  pur- 
pose of  advancing  our  knowledge  of  such  fundamen- 
tal subjects  as  physics  and  chemistry.  On  the  con- 
trary, if  true  to  his  name,  he  should  help  to  multiply 
them  many  fold  in  the  interest  of  economic  and 
commercial  development. 


[  88 


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